Former Alabama Chief Justice Roy Moore sailed to victory last night over incumbent Sen. Luther Strange in Alabama’s special Senate election primary runoff. The race was called shortly after the polls closed, with Moore beating Strange 57% to 43%. Vote counters estimated a low turnout with around 15% of eligible voters coming out for the election. But it’s far more important than that indicates — it’s a marker in estimating President Donald Trump’s hold on the GOP.

Strange was appointed to the Senate seat by former Gov. Robert Bentley in February after Jeff Sessions left it to become attorney general. It was thought at the time that Strange would hold the seat until the next general election in 2020, but politics threw him a curve. Bentley was removed from office after it was discovered he was using state funds to hide an affair. Lt. Gov. Kay Ivey replaced Bentley and called for a special election in December.

Strange, a former state attorney general who’d pushed to suspend impeachment proceedings against Bentley, bore the marks of the latter’s corruption. He soon found himself in a crowded primary battle with eight other Republicans. When no one emerged from the primary with a majority of the vote, the top two finishers, Strange and Moore, squared off.

The primary and the runoff, as with all special elections, was framed by some as a referendum on President Donald Trump, but more so it was one on the “establishment.” Trump was vocal in his support of Strange, and he made an appearance in Alabama on his behalf during the campaign. Vice President Mike Pence also turned out for Strange. Strange, in turn, has been a loyal supporter of Trump in the Senate — a reliable conservative vote.

What may have fatally wounded Strange, however, was that Senate Majority Leader Mitch McConnell also voiced support for him in the runoff and provided $9 million from the Senate Leadership Fund for Strange’s campaign. Moore used this support from the leadership as a means of attacking Strange and linking him to what he called “DC’s slime machine.” It worked.

Moore had some heavy-hitting support of his own during the race. Among those who came out for his campaign were Chuck Norris, Sarah Palin and former Trump adviser Steve Bannon. Bannon’s entry into the fray on behalf of Moore suggested that this race was going to be a proxy fight between competing visions of the GOP’s future. Just who represented what was grounds for widespread speculation, and the Trump haters (who hate Bannon even more, if that’s possible) were giddy at the possibility of this election leading to a civil war within the Republican Party.

Moore is perhaps best known for his refusal in 2003 to remove a display of the Ten Commandments from the Alabama state courthouse while serving as chief justice of the Alabama Supreme Court. His defiance of the federal court order cost him his job, but he won it back in 2013, only to lose it again three years later for ordering judges not to issue same-sex marriage licenses. On Monday, Moore demonstrated his support for the Second Amendment by drawing his gun at a campaign rally, a move that left Democrats with a case of the vapors. Few can question Moore’s conservatism and his dedication to principle. Some have wondered, though, if Moore will be able to play well with others in the Senate should he win the general election in December. His conservative credentials will serve the Republican agenda well, but his maverick style could do the opposite by adding more chaos to the unpredictable political climate.

Moore will face former U.S. attorney Doug Jones in the general election on Dec. 12. Jones won the Democrat primary in August. A win for Moore is crucial for Republicans. They have a majority with just 52 seats, and we already know that this isn’t enough to keep two or three rogues from blocking their own party’s agenda.

Moore has in his favor the fact that Alabama is a solid GOP state that has elected Republicans to the U.S. Senate continuously since 1997. In Sessions’ last election as senator in 2014, he ran unopposed. Trump won the state last year with 62% of the vote. This last fact could be pointed to as a reason for Republicans to be optimistic, yet cautious, given Trump’s volatility with the electorate. Democrats are sure to make the race about him, and it can be expected that they will nationalize the race. It could be a long wait until December.