Donald Trump is entering the second year of his presidency, but he and Republicans in Congress will need to govern as though it's his last.

After months of inaction on the top items in their shared legislative agenda, they closed out 2017 with a bang. A tax reform bill that also repealed Obamacare’s individual mandate and allowed drilling in the Arctic National Wildlife Refuge became law in December, capping a busy year of deregulation, military gains against the Islamic State, and successful conservative judicial nominees.

Trump and congressional Republicans won’t have the luxury of a late legislative windfall in 2018. This year, the entire House and a third of the Senate is up for re-election. The closer it gets to November, the harder it will be to get Republicans seeking another term to take difficult votes. Democrats are expected to make gains, having already reduced the GOP Senate majority to a razor-thin 51-49 margin with an improbable win in Alabama. If they capture one or both houses, Republicans may never have another chance to pass conservative legislation unimpeded by the opposition.

"The Trump White House and congressional Republicans know that if they want to maintain their majority in the House of Representatives and possibly make gains in the Senate, they cannot rest on their 2017 accomplishments, they have to continue racking up legislative wins," said GOP campaign veteran Ford O'Connell. "This won’t be easy because they have a limited window before scores of members forsake their legislative duties and start worrying about their political livelihoods. Expect legislative dealings to halt by the summer of 2018."

“He … needs to keep working on unwinding Obamacare and get as many federal judges confirmed as is humanly possible,” said Republican consultant Brad Todd.

Once must-pass items such as funding the federal government, renewing the Children’s Health Insurance Program, and extending the debt limit are dealt with, Trump will have little time left to break ground on the border wall and a new infrastructure package, among other top White House priorities.

[Look Ahead: Donald Trump's 2018 agenda]

“I think that [Deferred Action for Childhood Arrivals], infrastructure, CHIP, and maybe some type of Obamacare/Trumpcare fix would be as far as he could go,” said Jim Dornan, a Republican strategist. “He's going to need Democrats on any legislation and those are the only issues on which they might be able to find common ground.”

If the GOP loses the Senate, Trump will have difficulty filling any Cabinet vacancies that come up in the second half of his term. (AP Photos)

Besides enacting as much of their platform as they can while they still have the votes to do so, Trump and Republicans must also fulfill campaign promises, accelerate economic growth, and create jobs in order to minimize their losses by rallying the base and win new converts.

“It's always best to have low expectations of legislative success during competitive midterms, and this year is no different,” said GOP strategist Alex Conant. “Republicans would love to run on a record of accomplishment, so I expect them to push a broad agenda and then see if anything gains bipartisan momentum. Clearly, infrastructure and immigration would appear most likely.”

That’s without even considering the fact that many Democrats want to actually make 2018 Trump’s last year in office. Fewer than 60 liberal backbenchers in the House were ready to advance articles of impeachment being pushed by Rep. Al Green, D-Texas. But if Democrats win back the House, impeaching Trump becomes a legitimate option — even if a Senate conviction, which requires a two-thirds majority vote, remains a tall order. Billionaire environmentalist Tom Steyer, a Democratic mega-donor, is already making impeachment a litmus test.

"As of right now, Democrats are a slight favorite to win the House," said O'Connell. "That said, Republicans want to show that they can govern. Further, congressional Republicans want to make the case to some of their constituents that you do not have to like Trump to appreciate what is being accomplished. They are hoping legislative accomplishments can stem the tide of the Democrats' 'impeach Trump' mantra."

If the GOP loses the Senate, Trump will have difficulty filling any Cabinet vacancies that come up in the second half of his term. A Democratic majority in the upper house could also put the brakes on Trump’s transformation of the federal judiciary by blocking his conservative nominees, to say nothing of what would happen if there was another opening on the Supreme Court. After watching Republicans block former President Barack Obama’s nomination of Merrick Garland for a year and then change filibuster rules to expedite the confirmation of Neil Gorsuch, Democrats won’t be in the mood to confirm Trump justices.

Nevertheless, Trump and his supporters remain optimistic. “If the president's impressive first year in office is any indication, the American people have a lot to look forward to in 2018,” said Erin Montgomery, communications director for the Trump-aligned America First Policies. “Keeping more of their hard-earned money thanks to the president's tax cut; the revamping of an immigration system that has failed us for far too long; and perhaps a rebuilding of our nation's infrastructure.”

Even with Republican majorities, however, keeping a fractious group of lawmakers together long enough to get bills on the president’s desk is no easy task.

"The White House will have a small window to get any priorities through Congress,” said Jason Pye, vice president for legislative affairs at FreedomWorks. “Obviously, the first real test will be funding the government past January 18 and reauthorizing [the Foreign Intelligence Surveillance Act]. The problem the White House is running into is that conservatives want to see spending cuts — including mandatory spending reforms, which will be the driver of long-term budget deficits — and surveillance reforms that protect Americans' civil liberties. It doesn't appear that the White House has the same concerns about budget deficits and the Bill of Rights.”

Immigration reform

Senate Minority Leader Chuck Schumer, D-N.Y., and House Minority Leader Nancy Pelosi, D-Calif., came away from a September meeting with President Trump agreeing to fight over the wall another time. (AP Photo)

Another big test is immigration. Last year, Trump decided to rescind DACA effective March 5, giving Congress an opportunity to pass a law codifying Obama’s executive action protecting undocumented immigrants who came to the U.S. as minors. Trump and his allies on Capitol Hill would like to get certain immigration policy concessions in return for extending the DACA recipients’ legal status.

“We must BUILD THE WALL, stop illegal immigration, end chain migration [and] cancel the visa lottery,” Trump tweeted after meeting with Senate Republicans about DACA strategy. “The current system is unsafe [and] unfair to the great people of our country — time for change!”

[Look Ahead: Trump's 2018 immigration plan]

Some Republicans who disagree with the president on immigration appear willing to strike such a deal. “Obama couldn't do it. Bush couldn't do it. I think you can do it,” Sen. Lindsey Graham, R-S.C., said at the White House immigration meeting last week. “There's a bill to be had. If you want it bad enough, we'll get it and it will be good for the country. Everybody has got to give a little bit.”

“We can fix DACA in a way that beefs up border security, stops chain migration for the Dreamers, and addresses the unfairness of the diversity lottery,” tweeted Sen. Jeff Flake, R-Ariz. “If POTUS wants to protect these kids, we want to help him keep that promise.” Flake had cited the growing influence of immigration hawks in the Republican Party as a factor in his decision not to seek re-election this year.

But some Democrats want to pass the DREAM Act, which offers legal status to a larger population than is currently protected by DACA, without any strings attached. Their bill has four Republican co-sponsors in the Senate, where bipartisan comprehensive immigration reform has gotten more than 60 votes before. Members of the Congressional Hispanic Caucus are willing to risk a government shutdown by attaching an immediate DACA fix to the spending bill, although they have been rebuffed in the past.

Outside liberal groups are trying to keep up the pressure on legislators in both parties they describe as belonging to the “Deportation Caucus.” They emphasize that Dreamers are losing their work permits now, which places them in financial and legal jeopardy. And even if DACA is extended, it could take up to six weeks to get the program up and running properly. Rep. John Yarmuth, D-Ky., told the Washington Examiner last year that he doubted Republicans “can afford to alienate the entire Hispanic world in an election year.”

The wall is also offensive to many Democrats, who regard its inclusion as a poison pill that would kill a deal. Trump has been inconsistent on how important the wall is as a condition for continuing DACA. Senate Minority Leader Chuck Schumer, D-N.Y., and House Minority Leader Nancy Pelosi, D-Calif., came away from a September meeting with Trump agreeing to fight over the wall another time, an account the White House essentially corroborated. But just this month, Trump declared, “Any legislation on DACA must secure the border with a wall.”

Trump’s feud with former White House chief strategist Steve Bannon could also affect his ability to get an immigration deal done. Bannon’s Breitbart News has been ground zero for opposition to amnesty for illegal immigrants. In an immigration speech reportedly co-written by Bannon, then-candidate Trump described DACA as one of “President Obama’s two illegal executive amnesties” and pledged to “immediately terminate” it.

Whether any deal is viewed as a win by immigration hawks rather than a Trump capitulation on amnesty will come down to not only the details of the final product, but how those details are covered by sites such as Breitbart, which have helped rally conservatives against immigration legislation in the past. Trump has so far had the upper hand in his battle with Bannon, but there is no guarantee that will continue if he signs an immigration bill seen as a disappointment.

“The base and the people that supported this president supported the president and supported his agenda,” insisted White House press secretary Sarah Sanders at a briefing last week. “Those things haven’t changed. The president is still exactly who he was yesterday as he was two years ago when he started out on the campaign trail.”

Infrastructure and welfare reform

While the Trump administration struggled to keep the public focused on “Infrastructure Week” last year, it’s an issue likely to be revisited. It does not hurt that Transportation Secretary Elaine Chao is the wife of Senate Majority Leader Mitch McConnell.

Infrastructure is another issue on which Trump can work with Democrats while also creating some construction jobs to build on the economic momentum carrying his own party into the midterm elections. Many Republicans initially viewed this as a $1 trillion boondoggle, like the Obama stimulus program, but some of them have since warmed to the idea. It does not hurt that Transportation Secretary Elaine Chao is the wife of Senate Majority Leader Mitch McConnell, R-Ky.

“First, [an infrastructure bill] is needed and I don’t think many dispute that,” said Republican strategist Christian Ferry. “Second, it is an opportunity for bipartisanship which might show Congress to be a functional institution for a change. Third, if Democrats want to continue to play the obstruction game, Republicans should dare them to vote against fixing a bridge or highway in their home district heading into midterm elections.”

“I think the president needs to dare the Democrats to oppose him on a realistic infrastructure proposal and regulatory reform,” Todd concurred. While the Trump administration struggled to keep the public focused on “Infrastructure Week” last year, it’s an issue likely to be revisited now that taxes are out of the way.

Trump isn’t the only person eager to see more of the Republican agenda become law before November. So is House Speaker Paul Ryan, R-Wis., who has faced questions about his political future with the GOP majority in play. Ryan would like to pursue welfare reform and toughen work requirements, part of his longstanding commitment to overhaul entitlements. Trump has sounded supportive, despite his lack of enthusiasm for Ryan-style entitlements changes during the campaign.

"We’re looking very strongly at welfare reform, and that’ll all take place right after taxes, very soon, very shortly after taxes," Trump said at the White House in November. Other Republicans are more skeptical of bringing up welfare or entitlements in an election year, including McConnell.

“There is no way that entitlement or welfare reform will see the light of day,” Dornan said. “That was the talk from folks a little drunk on tax reform.”

Trump is already pushing a major expansion of offshore drilling in an effort to create jobs and boost domestic energy production. “We are embarking on a new path committed to energy dominance in America,” Interior Secretary Ryan Zinke told reporters as he unveiled the draft proposal. “This is a clear difference between energy weakness and energy dominance. We are going to become the strongest energy superpower.”

The plan to make more than 90 percent of the total acres on the Outer Continental Shelf available for leasing drew immediate pushback from coastal governors and lawmakers, including Republicans. One opponent is Florida Gov. Rick Scott, a Trump ally the president would like to see challenge Sen. Bill Nelson, D-Fla., to help protect the Senate majority. Sen. Marco Rubio, R-Fla., is also against it.

“The issue for me has ultimately always been about local control,” said Rep. Mark Sanford, R-S.C., a Freedom Caucus member, in a statement announcing his opposition. “Whether you are for or against offshore drilling, I think we could all agree that locals should have some degree of voice on what happens in their backyard.” The details could in fact change as a result of this local feedback.

Democratic opposition

Senate Democrats speak to the media.

For Trump, the bigger obstacle to his 2018 agenda will be Senate Democrats. Even though 10 Democrats are seeking re-election in states he carried in the presidential race, they have so far not budged in voting with their party against the president. This includes Sen. Joe Manchin, D-W.Va., who is running for another term in a state Trump won by 42 points.

“He talks. But he doesn’t do anything. He doesn’t do,” Trump complained to the New York Times about Manchin. “'Hey, let’s get together, let’s do bipartisan.' I say, ‘Good, let’s go.’ Then you don’t hear from him again.”

“Will the Democrats be unwilling to contribute to any Trump victory in order to continue to beat him up until November?” Dornan asked. “Or will they sense that voters are looking for solutions and their obstinacy could cost them at the polls? I'm not sure anyone has the answer to those questions yet. The budget talks may give us a clue.”

[Look Ahead: Democrats hope 2018 is the year they take back power from Trump]

Democrats running in educated, suburban districts where “the Resistance” is strong may come up with different answers to those questions than those representing rural or white working-class areas where the president is still popular.

A lot of factors remain outside Trump’s control. The Russia investigation is one. Any developments with special counsel Robert Mueller’s probe could deflate the president’s agenda. And foreign crises such as the tension with nuclear-armed North Korea or the protests in Iran could also demand Trump’s attention.

“There is plenty of opportunity on the international agenda,” Conant said. “We could see more sanctions for human rights violators and action to safeguard elections if the White House is willing.”

After a flurry of executive actions, Trump got off to a slow start working with Congress. With the momentum of the tax bill behind him, he will have to keep his foot on the gas pedal for the remainder of this year.