Tuesday marks the end of one expensive and heated contest — and possibly the beginning of another. 

Alabama voters will head to the polls Tuesday to decide who will get the Republican Senate nomination — the incumbent, Sen. Luther Strange, or former Alabama chief justice Roy Moore. 

The vote will end a contest pitting Moore’s solid base against Strange’s tireless efforts to transform himself into a proxy for President Trump, who remains popular among GOP voters in the state. The winner will face former U.S. attorney Doug Jones, the Democratic nominee, in a Dec. 12 general election. 

While the policy differences between Strange and Moore are negligible, the campaign has turned into a proxy war for factions within the national Republican Party, both seeking Trump’s favor while crossing swords over the party’s congressional leadership, particularly Senate Majority Leader Mitch McConnell, R-Ky.

Below are five questions whose answers will be key to the outcome. 

1. Will voters see Donald Trump in Luther Strange?

Strange’s campaign has one overriding theme: He loves the president — a whole lot — and hopes you understand the depths of his commitment. The incumbent speaks of Trump in terms that are never less than reverent (and sometimes, biblical). He gives unqualified support for a border wall with Mexico and (like Moore) bills repealing the Affordable Care Act — many of which included Medicaid cuts with potentially serious consequences for Medicaid recipients, Alabama hospitals and primary care providers.

The senator attacks Moore for slights real or perceived against Trump and suggested at a debate Thursday that Moore resented Strange's friendship with the president. The strategy helped Strange slide into the runoff ahead of Rep. Mo Brooks on Aug. 15 and helped him secure an appearance by Trump at a rally in Huntsville last week. 

Moore, though, has also said he will support the president’s agenda in the Senate and that he's not running against the president. Consultants said Friday that Strange’s relentless invocation of Trump has meant Strange has disappeared as a person. Trump himself seemed to hedge on his support for Strange at Friday’s rally, suggesting Moore might win and that if he did, he would campaign for him. 

President Trump applauds Luther Strange after speaking at a campaign rally on Sept. 22, 2017, in Huntsville, Ala.

2. Will voters see Robert Bentley in Luther Strange?

Strange’s appointment to the Senate by former governor Robert Bentley — when Strange was Alabama attorney general — continues to haunt the campaign. Bentley pleaded guilty to two campaign finance violations and resigned from office in April after an investigation by a unit of the attorney general’s office. Strange interviewed for and accepted the appointment while the investigation was underway. 

The incumbent has declined to say what role, if any, he had in the investigation. Moore tried to press him on the issue at Thursday’s debate. Strange did not answer, nor did he answer when asked by reporters following the debate. 

Moore has said little about the appointment in his advertising, but outside groups opposed to Strange have repeatedly brought it up.

3. Can Roy Moore’s base carry him to another victory?

Moore has run the same race he’s run since 2000, counting on enthusiastic supporters and high name recognition to make up for deficits in fundraising and television exposure. He has done so against a virtual tsunami of money coming into the race: Strange and the McConnell-aligned Senate Leadership Fund (SLF) spent a combined $10 million on the campaign through Sept. 6, and even more in the weeks after. Moore’s campaign spent just $1.1 million through early September.

Strange and the SLF tried a variety of approaches to peel off Moore’s base — first trying to raise questions about payments to Moore from the Foundation for Moral Law, which he headed from 2003 to 2012, and then by raising questions about Moore’s preparedness, citing a July radio interview where Moore did not appear to know what the Deferred Action for Childhood Arrivals program was. 

In recent weeks, Strange has switched tactics, suggesting Moore would not be a reliable vote for Trump and questioning his commitment to such issues as the construction of a border wall. Moore says that he favors the wall but suggests other, more immediate measures need to occur. 

Roy Moore walks into the RSA Activities Center for a debate with Luther Strange on Sept. 21 2017, in Montgomery, Ala.

4. Which will be more decisive — national politics or Alabama dynamics?

This race is an oddity: an off-year primary that has become a battleground among GOP factions. Vice President Pence traveled to Birmingham on Monday to campaign for Strange, and both the National Rifle Association and the U.S. Chamber of Commerce are trying to push the incumbent over the finish line. Moore, meanwhile, has won the support of members of the conservative House Freedom Caucus and former Trump adviser Steve Bannon. Former GOP vice presidential nominee Sarah Palin and former Trump adviser Sebastian Gorka appeared at a rally for Moore last week.

As Strange has touted his support from Trump, Moore has attacked Strange for his support from McConnell and promised to work to oust him as leader should he get to the Senate. Strange has tried to distance himself from McConnell, and at the Huntsville rally last week Trump suggested the two senators barely know each other.

Moore's loyal following from Alabama voters comes from his high-profile fights over the Ten Commandments and same-sex marriage, both preceding Trump's election.  In a race with turnout projected between 12% and 15%, the performance of Moore’s traditional bastions could prove crucial. 

5. Where does this leave Doug Jones?

The Democratic nominee will have his work cut out for him, mo matter who wins Tuesday. No Democrat has won an election to the U.S. Senate in Alabama since 1992, and the last statewide election the party won took place in 2008. If turnout in the Republican primary (423,000 voters) was low, turnout for the Democratic primary — won overwhelmingly by Jones — was still lower (165,000). The party has long been in a rebuilding mode.

Still, Democrats appear to be enthusiastic for their candidate — a former U.S. attorney who successfully prosecuted two of the 16th Street Baptist Church bombers — and the national party is taking notice. Former vice president Joe Biden will appear at a rally for Jones in Birmingham next week. 

The Republican nominee will enter the general election campaign as the heavy favorite,  but both GOP candidates have flaws. Strange struggles to create energy among Republican voters, and Moore’s outspoken opposition to homosexuality has turned off the business wing of the party. Moore eked out a win against Democrat Bob Vance in the 2012 campaign for chief justice of the state Supreme Court — finishing well behind the Republican ticket that year — and Democrats will likely be studying that race closely as they move forward for Jones.