Appointed Sen. Luther Strange, R-Ala., will face off against Judge Roy Moore in a late September runoff to determine who will fill the remainder of Attorney General Jeff Sessions' Senate term.

Moore finished first with nearly 40 percent of the vote to Strange's 32 percent. The interim incumbent received a late boost from President Trump. Trump endorsed Strange last week, cut a robocall for him Monday, and sent out multiple laudatory tweets backing his candidacy heading into the special Republican primary election. Vice President Mike Pence also tweeted out his endorsement of Strange hours before the polls closed on Tuesday.

Strange's top-two finish is also a victory for Senate Majority Leader Mitch McConnell, R-Ky. The Senate Leadership Fund, a McConnell-backed super PAC, relentlessly attacked a third candidate, Rep. Mo Brooks, R-Ala., for not being pro-Trump enough and for backing Sen. Ted Cruz, R-Texas, during the Republican presidential primary last year. Ultimately, they poured nearly $4 million into the race against Brooks, who finished third with nearly 20 percent of the vote.

Throughout the race, Brooks became known for his anti-McConnell rhetoric. He promised not to support him as majority leader moving forward, going so far as to put a "Ditch Mitch!" banner on his campaign bus in the final days. Brooks also said in a TV ad that McConnell and Strange are "weak."

Trump's endorsement all but ended any hopes Brooks had of reaching the runoff. A House Freedom Caucus member, Brooks was backed by top conservative personalities Sean Hannity, Mark Levin and Laura Ingraham. He asked the president to reconsider his support of Strange, to no avail.

Moore ended up cruising into the runoff against the incumbent Republican, largely ignored in the Strange versus Brooks infighting until late in the campaign. A longtime lightning rod for controversy in the state, Moore led in the polls heading into Tuesday. According to the final RealClearPolitics average, Moore led with 32.2 percent support to Strange's 28.4 percent. Brooks held only 17 percent support.

Moore is a well known political figure in the state after being removed as the state's chief justice in 2003 after a fight over the Ten Commandments monument at the state judiciary building and being suspended from the bench in 2016 after refusing to abide by the Supreme Court's ruling in favor of same-sex marriage in 2015.

This will also be Moore's third statewide campaign for higher office, including primary defeats for the the Alabama governorship in 2006 and 2010. He is popular among religious conservatives in the state, who make up a large portion of the Republican primary electorate.

Like the primary, big dollars are expected to flow and give Strange an outsized advantage over the former Alabama chief justice. According to the latest Federal Election Commission filings, Strange himself raised $2.9 million in the most recent cycle, while Moore raised only $463,000. Additionally, SLF is expected to spend upwards of $4 million against Moore.

The runoff will be held on Sept. 26, with the winner moving on to the general election on Dec. 12. Doug Jones secured the Democratic nomination Tuesday night, easily exceeding the 50 percent threshold to avoid a runoff.