Senate Democrats face a daunting challenge in trying to hold their majority in 2024. A big question, early in the election cycle, is just how difficult the map gets for the party.
Democrats emerged from the 2022 midterm elections in a fairly happy position, with a 51-49 majority. It’s not a huge edge but enough to confirm President Joe Biden’s judicial and political nominees. Senate Democrats also can pass their favored legislation, though it’s likely to face a wall in the Republican-majority House.
DEMOCRATS FACE UPHILL BATTLE TO MAINTAIN SENATE MAJORITY IN 2024
Senate Democrats got to this point by upending dire pundit predictions about the 2022 midterm elections. Two years into Biden’s White House term, Senate Democrats grew their margin by one, making them no longer so reliant on Vice President Kamala Harris’s tiebreaking vote in a 50-50 Senate.
That era of political good feeling is likely to be short, though. The 2024 election cycle figures to be an uphill slog for Senate Democrats, with Republicans on the offense in aiming to win several blue seats in otherwise red states. Democratic incumbents face reelection in states that have become increasingly hostile to the party, including Montana, Ohio, and West Virginia. Sens. Jon Tester (D-MT), Sherrod Brown (D-OH), and Joe Manchin (D-WV) each won reelection in 2018. Yet those elections took place in a heavily Democratic-leaning environment that they can’t count on having again in 2024.
Meanwhile, other Democratic-held seats are in some of the same hotly contested states that were at the center of the 2022 midterm elections, including Arizona, Nevada, and Pennsylvania. In total, Democrats will be defending 22 seats, to 10 by Republicans, and Sen. Kyrsten Sinema (I-AZ) presumably seeking reelection after bolting the Democratic Party in December. (Sinema still gets her Senate committee assignments from Democrats, maintaining the party’s 51-49 majority.)
Senate Democrats also have few real targets as 2024 pickups.

Their best shot might be the reelection bid of Sen. Rick Scott (R-FL). Scott drew negative media coverage over 2022 policy proposal plans that Democrats panned as calling to end Social Security and Medicare, among other critiques. Still, Scott, a healthcare mogul from his private sector days, can self-fund a reelection bid if necessary. And he’s proven a durable political candidate, twice winning Florida’s governorship and then beating an incumbent Democratic senator in 2018.
Texas is the only other possible Democratic target, and that’s a real stretch. Sen. Ted Cruz (R-TX) is seeking a third term.
Texas has become a shade more purple in recent years, yet Democrats still struggle statewide. Cruz in 2018 beat then-Rep. Beto O’Rourke, at the time a rising Democratic star, 50.9% to 48.3%. Yet that still translated into a nearly 215,000-vote Cruz reelection win out of more than 8.3 million votes cast.
If there’s any good news for Democrats, it’s that the last time this class of senators was up for reelection, in 2018, Republicans effectively picked off the politically lowest-hanging fruit and maintained their Senate standing despite being the party in power. In the midterm elections that year, halfway through former President Donald Trump’s single White House term, and even as House Democrats won the majority for the first time in eight years, Democratic senators lost in Indiana, Missouri, and North Dakota. Those seats are now all safely Republican in the 2024 cycle. Democrats will aim to return the favor.
Senate Democrats are also buoyed by the return of their 2022 campaign chief, Sen. Gary Peters (D-MI). Peters on Jan. 9 agreed to helm the Democratic Senatorial Campaign Committee for another election cycle after Senate Majority Leader Chuck Schumer (D-NY) had struggled to find a willing campaign chief for his caucus.
To be sure, the 2024 elections are 22 months away, an eternity in politics. Lots can change and no doubt will.

Moreover, the dynamic of the campaign for a Senate majority could be influenced by a variety of outside factors. Particularly the presidential election and the attention it generates. Biden, 80, has said his “intention” is to run for reelection and that he will make a final decision in the early months of 2023. Trump has already announced a third White House bid, while multiple other Republicans are lining up to launch campaigns.
The eventual set of nominees could have a profound impact on down-ballot races, including those for the Senate. But at this early stage, here are the top Senate races in which Democrats will likely be on the defensive.
Arizona
Senate Democrats’ quest to hold their majority grew at least somewhat more complicated with Sen. Kyrsten Sinema’s switch to being an independent. That after a career as a Democrat in the Arizona State Legislature, six years in the House, and her first four years in the Senate.
From Sinema’s electoral perspective, though, the move makes sense. She’s long been under fire from more left-wing colleagues, including in August using her leverage in the 50-50 Senate to preserve a tax code provision known as the “carried interest loophole,” which allows private equity professionals to pay lower investment tax rates on their pay, based largely on investments, than most salaried and hourly workers.
Had she stayed a Democrat, Sinema would have faced a primary from Democratic Rep. Ruben Gallego, with whom she’s feuded for years. Gallego declared for the Senate on Jan. 23 after months of signaling the move.
Gallego, first elected to a deep-blue Phoenix-based House seat in 2014, has a compelling biography. The Chicago native, of Mexican and Colombian descent, was raised by a single mother and went on to graduate from Harvard. Gallego is a Marine combat veteran, having served and deployed as a corporal during Operation Iraqi Freedom. But Gallego’s liberal voting record could make the House Progressive Caucus member a tough sell statewide in Arizona, which has emerged as a quintessential swing state.
Though Sinema won’t have to face a competitive Democratic primary challenge, her general election prospects are uncertain. Arizona is a bona fide purple state after decades as a red bastion. A strong 2024 Republican nominee could win, with the independent and center-left votes split between Sinema and a Democratic Senate rival.
The trick for Republicans in trying to pick off this Senate seat is nominating a candidate palatable to the general electorate in fall 2024, not just conservative activists in the GOP primary. In 2022, Republicans nominated investor Blake Masters to run against Democratic Sen. Mark Kelly. Masters, a first-time candidate, committed a series of campaign gaffes and came up short against Kelly. Also last year, Arizona Republicans lost races for governor, secretary of state, and attorney general by nominating prominent deniers about Biden’s defeat of Trump in the 2020 White House race, as Democrats portrayed the office-seekers as fringe characters uninterested in the concerns of everyday Arizonans.
Republicans would love to have former Gov. Doug Ducey run for Senate. Ducey, a school choice champion, left office in early January after eight years with high approval ratings. But he demurred from a 2022 Senate race after clashing with Trump over the validity of presidential race results from two years earlier when Biden became only the second Democratic nominee since 1948 to win the Grand Canyon State’s Electoral College votes. So far, there’s no indication Ducey is interested in reentering the political fray.
Plausible Republican Senate candidates include Pinal County Sheriff Mark Lamb and State Treasurer Kimberly Yee, among others. The GOP Senate primary isn’t until August 2024, so there’s still time for candidates to join, in a state with a deep Republican bench.
Michigan
Democratic Sen. Debbie Stabenow’s Jan. 5 announcement that she won’t seek reelection in 2024 gives Republicans an unexpected pickup opportunity. Stabenow had been expected to run again, and she would have been tough to beat. Stabenow did, after all, defeat incumbent Republicans to claim seats in the House in 1996 and then the Senate four years later. She’s chairwoman of the Senate Agriculture, Nutrition, and Forestry Committee and a member of Democratic leadership.
Still, Michigan figures to be one of the tougher states for Republicans as it moved considerably to the left in the 2022 midterm elections. Democratic Gov. Gretchen Whitmer easily won reelection, and her party won control of both chambers of the state legislature for the first time in nearly 40 years. And a pair of House Democrats, Rep. Elissa Slotkin in the Lansing and northwestern Detroit exurbs 7th Congressional District, and Rep. Dan Kildee, in the Flint and Tri-Cities areas 8th Congressional District, beat highly touted GOP rivals. Democratic Rep. Hillary Scholten won the newly created Grand Rapids and Muskegon area 3rd Congressional District.
Nonetheless, like Pennsylvania and Wisconsin, the Wolverine State will be a top target for Republicans in the presidential race. The industrial state trio was, of course, crucial to Trump’s surprise 2016 presidential victory over Democratic nominee Hillary Clinton — which will no doubt gin up excitement and turnout on both sides for the Senate contest.
One likely Democratic candidate is Slotkin. She might have an easier time winning statewide than in her swing district, where in 2020 Biden would have only narrowly beaten Trump, 49.4% to 48.9%.
Another prominent Democrat reportedly eyeing the Senate race is state Sen. Mallory McMorrow. She became a progressive hero of sorts after an April 2022 Michigan Senate floor speech in which she rejected a Republican campaign fundraising email that claimed McMorrow wanted to “groom and sexualize” kindergarten students.
Republicans don’t have as many first-tier options besides freshmen Rep. John James, who represents the Macomb County 10th Congressional District. James, a West Point graduate and businessman, was the Republican Senate nominee in 2018 and 2020 but lost both times. He may not want to risk the House seat he just took on for an iffy race in a state that’s moving toward Democrats.
Yet there are plenty of other credible possible Republican Senate candidates. That includes, among others, former Rep. Mike Bishop, ex-state Attorney General Mike Cox, Rep. Bill Huizenga, Rep. Lisa McClain, and former state Senate Majority Leader Mike Shirkey.
One GOP possibility Republican officials aren’t likely enthusiastic about is real estate agent Ryan Kelley, a 2022 gubernatorial aspirant. Kelley was arrested in June 2022 on misdemeanor charges related to his role in the Jan. 6 Capitol riot — amid a gubernatorial campaign that ended with a fourth-place primary showing. Kelley has pleaded “not guilty” to four misdemeanor charges, including “disorderly and disruptive conduct” in a restricted area and damaging a tarp “covering the northwest scaffolding” outside the Capitol as supporters of Trump tried to block congressional certification of Biden’s 2020 election win.
Montana
Sen. Jon Tester has been a Democratic rock star of sorts since beating an incumbent Republican senator in 2006. Tester has since twice won reelection in a solidly red state. Tester will be 68 in 2024, and while he hasn’t declared for reelection, he seems to be leaning toward running again.
Republicans are convinced Tester’s political luck has run out in Montana. In 2020, Trump easily beat Biden, 57% to 41%. And Tester’s Montana colleague, Sen. Steve Daines, is running the Senate campaign arm in the 2024 cycle and no doubt has a special interest in this race.
The chance to take on Tester could set up a fierce Republican primary contest between Rep. Ryan Zinke, a onetime Trump administration interior secretary, and Rep. Matt Rosendale.
Rosendale lost to Tester in 2018 before winning, in 2020, what was then Montana’s single, statewide House seat. Montana’s population grew so much in the decade prior to the 2020 census that starting Jan. 3, it has two House seats, for the first time in 30 years. Rosendale in 2022 easily won reelection to the new eastern Montana 2nd Congressional District seat. Zinke, meanwhile, won relatively narrowly in the western Montana 1st Congressional District.
During the vote for House speaker, which took 15 ballots and several days, Zinke was a consistent supporter of Rep. Kevin McCarthy (R-CA). Rosendale was among 20 holdouts against McCarthy, though their opposition melted early on the morning of Saturday, Jan. 7, when he and a handful of other GOP House dissidents voted “present,” a parliamentary maneuver that allowed McCarthy to claim the speaker’s gavel.
Zinke was a House member from 2015 until 2017 before Trump tapped him to lead the Interior Department. Zinke, a retired Navy SEAL, had to quit Trump’s Cabinet after two years. He faced mounting federal ethics investigations over his official travel. Problems included an inspector general report that Zinke violated the Interior Department’s travel policy by having his wife travel with him in government vehicles.
That’s all likely to be litigated if Zinke and Rosendale fight for the 2022 Republican Senate nomination. Still, it’s a prize worth having due to Montana’s consistent Republican fealty, giving the eventual nominee a real chance at beating Tester.
Nevada
Democratic Sen. Jacky Rosen is seeking a second, six-year term in one of the nation’s most competitive states. Democrats staved off disaster in the Silver State in 2022. Democratic Sen. Catherine Cortez Masto won reelection by less than 1 percentage point and only about 8,000 votes out of more than a million cast. And Nevada’s three Democratic House incumbents held on against well-funded GOP challengers. Still, Democratic Gov. Steve Sisolak lost reelection.
Nevada’s electorate is constantly churning, with new arrivals looking to try their professional and personal luck in the country’s gaming capital. In 2020, Biden beat Trump in Nevada relatively narrowly, 50.06% to 47.67%.
The Republican field against Rosen is still firming up. One possibility is Sam Brown, a retired Army captain who was awarded a Purple Heart after being severely wounded in Afghanistan. Brown sought the 2020 Republican Senate nomination but lost in the Republican primary to former state Attorney General Adam Laxalt, whom Cortez Masto then beat on Nov. 8.
Ohio
Democratic Sen. Sherrod Brown is a political survivor in a state moving away from his party. The staunch progressive has won three Senate terms over nearly 18 years, after 14 years in the House. Brown is a well-known political commodity in Ohio, going back to his eight years as secretary of state in the 1980s and earlier as a member of the state legislature.
Yet Brown’s Senate wins came when Ohio was more of a swing state. Former President Barack Obama carried the Buckeye State twice, and Democrats at the time routinely won statewide races. In recent years, though, Ohio has shifted to the right, with Trump winning the state twice by about 8 points.
Brown’s 2024 reelection bid will test if his brand of union-friendly, anti-corporate left-wing populism is still a draw in Ohio. The 2022 midterm elections didn’t portend well for that strategy, as Rep. Tim Ryan tried a version of it as the Democratic Senate nominee. Ryan lost to Republican Sen. J.D. Vance, an author, investor, and first-time candidate.
Brown is, of course, the original version, rather than a somewhat paler imitation. His championing of the working class has entailed longtime criticism of trade agreements that he says lowered import barriers and undermined American jobs with cheaper foreign labor. Over the years, Brown has advocated a variety of policies for workers, including a $15 minimum wage, expanding collective bargaining rights, and establishing a national fund to provide paid family and medical leave.
Republicans see Brown as a top 2024 target. The first Republican to launch a Senate bid, on Jan. 16, was state Sen. Matt Dolan, a part-owner of the Cleveland Guardians MLB team who lost to Vance in the 2022 GOP Senate primary. Dolan has the money to self-fund a campaign, which could scare off would-be GOP primary rivals.
Still, the Republican Senate primary field is expected to grow considerably. Candidates may include Rep. Warren Davidson, Ohio Secretary of State Frank LaRose, wealthy businessman Bernie Moreno, and state Attorney General Dave Yost.
Pennsylvania
Democratic Sen. Bob Casey will be running in a swing state that both parties desperately need to win the White House. Casey easily won reelection in 2018, but Pennsylvania has been competitive for Republicans, including in this year’s Senate race won by Democrat John Fetterman. Yet Republicans think the three-term senator will be vulnerable because he has become more liberal in recent years.
On the Republican side, David McCormick, who narrowly lost the 2022 Republican Senate nomination, is eyeing running again. The former hedge fund CEO and a Treasury Department official in former President George W. Bush’s administration could self-fund a Senate campaign.
Another Republican Senate candidate could be the third-place winner in the 2022 GOP primary, Kathy Barnette. She’s been a prominent MAGA activist who has promoted Trump’s false claims that he won the 2020 presidential race over Biden.
West Virginia
Sen. Joe Manchin may drive his fellow Democratic senators crazy sometimes, but they absolutely need him to seek reelection in 2024 to have any chance of holding the majority — or even to stanch the political bleeding. Manchin is the only Democrat with any chance of holding this Senate seat in a deeply red state. And even then, it’s an iffy proposition.
Manchin will be 77 in 2024 and hasn’t indicated his plans. Yet his decadeslong tenure in office suggests he may give it another go. Scion of a local political family in north-central West Virginia, Manchin was a state legislator for 14 years and then secretary of state for four. Manchin was West Virginia’s governor for six years, before winning his Senate seat in 2010.
He’s often a headache to his party, including driving down the cost of a signature Biden administration domestic initiative, the Inflation Reduction Act, from its original trillion-dollar-plus price tag. And he’s helped sink Biden nominations in the Senate, such as Neera Tanden for Office of Management and Budget director and Sarah Bloom Raskin for a top regulatory post at the Federal Reserve.
Still, Democrats know West Virginia voters generally hold a high opinion of Manchin, who is chairman of the Senate Energy and Natural Resources Committee. And they can let him off the hook for tough votes more in a 51-49 Democratic majority Senate, compared to the 50-50 tie of the past two years.
West Virginia in 2020 was Trump’s second-best state, and he won every county. Two years earlier, Manchin narrowly barely beat Republican Patrick Morrisey for reelection, 49.57% to 46.26%.
Manchin has already drawn a Republican challenger in Rep. Alex Mooney, who declared a week after winning reelection in the eastern and northern West Virginia 2nd Congressional District that he was setting his sights on higher office. Morrisey, West Virginia’s attorney general, may run for Senate again.
The biggest wild card in the race is the prospective candidacy of Republican Gov. Jim Justice, a longtime Manchin rival in state politics who recently suggested he’s inclined to jump into the Senate race. Justice has a net worth in the hundreds of millions of dollars, after inheriting a coal mining business from his father. Justice went on to build a business empire with over 94 companies, including the Greenbrier, a luxury resort in White Sulphur Springs, West Virginia. Justice has mused about a 2024 Senate run but hasn’t jumped in.
One factor possibly working in Manchin’s favor is Democratic growth, if slow, in West Virginia’s most populous areas. That includes Monongalia County, home to West Virginia University in Morgantown, and Jefferson County, located in the Eastern Panhandle of West Virginia and home to many remote workers and commuters to the Washington, D.C., area.
Both moved leftward in the 2020 presidential race and represent the kind of professional class workers who now make up the backbone of the national Democratic Party. All the while, West Virginia’s population is shrinking in the most heavily Republican areas, in the state’s eastern and southern realms, where coal mining and fossil fuel production are still important to local economies.
Wisconsin
Democratic Sen. Tammy Baldwin will be up for reelection in a 2024 presidential swing state. Baldwin has shown political durability in a career that began at age 24 with election to the Dane County Board of Supervisors, in and around the state capital of Madison, followed by the Wisconsin State Assembly, 14 years in the House, and election to the Senate in 2012.
Still, Wisconsin will be highly targeted by both presidential candidates. So Republicans will be tempted to run hard at Baldwin, who made history as the first openly LGBT woman elected to the House of Representatives and to the Senate. Baldwin has one of the Senate’s more liberal voting records. Though she is not as far to the left as Sens. Bernie Sanders (I-VT) and Elizabeth Warren (D-MA), among others.
The 2022 Wisconsin results were mixed. Republican Sen. Ron Johnson overcame a ferocious Democratic effort to unseat him. But Democratic Gov. Tony Evers also won reelection against a well-funded GOP rival.
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No Republicans have jumped into the Senate race. But an oft-mentioned GOP candidate is Rep. Mike Gallagher of the northeastern Wisconsin 8th Congressional District. Gallagher was an active-duty Marine Corps intelligence officer for seven years, including two deployments to Iraq. A Princeton University graduate with a doctorate from Georgetown University in government and international relations, among other academic credentials, Gallagher won his House seat in 2016. In the 118th Congress, Gallagher is chairman of the Select Committee on China in the Republican majority House.
David Mark is managing editor of the Washington Examiner magazine.