"A vote for Roy Moore is a vote for Donald J. Trump," declared former White House chief strategist Steve Bannon at a rally for the challenger on the eve of Alabama's Republican senatorial primary runoff.

Yet Bannon's erstwhile boss President Trump was tweeting, "Vote for Senator Luther Strange, tough on crime [and] border — will never let you down!" Trump followed up on Tuesday exhorting his followers to "get out and vote for Luther Strange" and "vote today for ‘Big Luther.'"

Strange, R-Ala., is the appointed incumbent but according to the public polling, he trails Moore, a former Alabama Supreme Court chief justice, in the race to finish the remainder of Attorney General Jeff Session's Senate term.

Alabama Republican primary voters headed to the polls Tuesday with a lot of lot issues on their minds, including the circumstances surrounding Strange's appointment. But the Moore versus Strange race has touched off a low-grade civil war in Trump world.

Most outside Trump supporters have weighed in on Moore's side, arguing that the "Ten Commandments Judge" will be more independent of Republican congressional leadership — and therefore potentially more supportive of the president. Bannon has contended that Senate Majority Leader Mitch McConnell, R-Ky., and House Speaker Paul Ryan, R-Wis., are obstacles to Trump's nationalist, populist agenda.

But the biggest outlier is Trump himself. He and Vice President Mike Pence have both traveled to Alabama to campaign for Strange. "Our president needs Luther Strange back in the United States Senate so he can finish the job," Pence said in Birmingham Monday night.

The Trump-aligned America First Policies spent half a million dollars on behalf of Strange in the waning days of the campaign. This put them in direct competition with their normal pro-Trump allies, the Great America PAC, which held a pro-Moore rally featuring former Alaska Gov. Sarah Palin and former Trump aide Sebastian Gorka.

Throughout his political career, Moore has focused on social issues. His refusal to comply with court rulings on same-sex marriage and his courtroom Ten Commandments display twice got him booted from Alabama's top judicial body.

Bannon nevertheless sees a rebuke to the Republican congressional leadership, and the election of a senator who is not beholden to them, as the best way to advance the issues more commonly associated with Trump. He said publicly that Moore beating Strange will show the world "that this populist, nationalist, conservative movement is on the rise."

With the Senate once again failing to pass a bill revamping Obamacare Tuesday, the Republican legislative agenda remains stalled. Although Trump has sparred with McConnell, especially on healthcare, the president is siding with the majority leader on Strange. GOP leaders believe their shared agenda would best be advanced by retaining a reliable Republican vote.

Many of Trump's supporters, however, think the solution might be electing another Republican who will rock the boat. After McConnell spent heavily to defeat him, Moore will owe McConnell — and the rest of what they call "the swamp" — nothing.

Trump has publicly cast doubt on whether Moore would be the same easy lay-up as Strange in the general election, although early polling has looked good for both Republican candidates. Sessions was last reelected with more than 90 percent of the vote, although he had no Democratic opponent. This time, the Democrats have already nominated former U.S. Attorney Doug Jones.

"I have to say this — Luther will definitely win. Roy has a very good chance of not winning — in the general election," Trump said during a rally in Huntsville, Ala., on Friday. In a radio interview Monday, he repeatedly called Moore "Ray."