President Trump’s approval rating is hovering around an all-time low, but you wouldn’t know that by following the Republican primary for Alabama’s U.S. Senate seat. Alabama Republicans will go to the polls next Tuesday to fill the seat left vacant by now Attorney General Jeff Sessions, and the three main candidates in the race — incumbent Sen. Luther Strange (he was appointed), Rep. Mo Brooks and former State Supreme Court Chief Justice Roy Moore — all are trying to tie themselves to Trump as tightly as possible.

That’s somewhat of a reversal for Strange, Brooks and Moore — all three declined to endorse Trump during the 2016 presidential primary. But times change; Trump is incredibly popular in Alabama. The president’s approval rating is at 85 percent among likely primary voters. Through Tuesday, none of these primary candidates had seemed to convince Republican voters that he was the person to best carry out the president’s agenda. That may change with Trump’s Tuesday night endorsement of Strange.

Trump’s backing of Strange could have a big effect, but for now, Tuesday’s primary looks like it will go down to the wire. Any of the three candidates could finish first or second, which would get them into a September runoff if, as expected, no candidate reaches 50 percent on Tuesday. Moore and Strange have traded first and second place in the limited polling we have, but Brooks is close enough that any two candidates could conceivably make the runoff.

If Moore advances to the runoff, it will be because of strong backing from religious conservatives. Although Moore is seen as a Trump-like populist, he’s best known not for his economic message, but for his religious one. As chief justice of the state supreme court, he refused to remove a monument to the Ten Commandments from the rotunda of the Alabama State Judicial Building, even though he was ordered by a federal court to do so. He’s been endorsed mostly by religious conservatives such as Alan Keyes, Chuck Norris and radio talk show host Steve Deace, who once said Trump’s nomination was a “sad day for America.”

Indeed, the few polls we do have show that Moore’s base is heavily evangelical Christian. In the latest JMC Analytics and Polling survey, Moore is well ahead of the pack among self-described evangelical Christians, with 38 percent. He’s in a distant third place among those who say they aren’t evangelical, with just 14 percent. Trump, for comparison, won about an equal share of the vote among born-again/evangelical Christians and non-evangelicals in the 2016 Alabama presidential primary. Moore’s support looks a lot more like that of another recent populist Republican president nominee: Mike Huckabee in 2008. Huckabee also had a greater than 20-point gap in vote share among evangelicals and non-evangelicals in Alabama. He also happened to be endorsed by Deace and Norris in 2008.

If Strange advances to the runoff, it will be in no small part because of the backing he’s gotten from the GOP establishment. He’s been endorsed by Senate Majority Leader Mitch McConnell and has the backing of McConnell’s Senate Leadership Fund PAC, which has spent millions on the race. Of course, being seen as the establishment figure isn’t necessarily helpful these days. Not only was Strange appointed to the seat by former Gov. Robert Bentley, who had to resign in disgrace, but McConnell is generally not well liked by Trump voters nationally. Interestingly, however, the establishment label doesn’t seem to be hurting Strange with Trump supporters or Trump himself, despite Trump’s recent lashing-out at Senate Republicans. Not only did Trump endorse Strange, but the Red Racing Horses poll reveals that Strange’s greatest support is among Republicans who strongly approve of the job Trump is doing.

Additionally, the National Rifle Association, which Brooks had hoped to corral earlier in the primary season, is with Strange. He’s also been endorsed by National Right To Life. The JMC Analytics and Polling poll found Strange with an equal amount of support from both evangelical and very conservative voters as among non-evangelical and somewhat conservative voters, respectively.

If Brooks advances to the runoff, it’ll be quite astounding given the onslaught of negative ads he’s faced. Most of McConnell’s fire has been trained on Brooks for being insufficiently pro-Trump. A McConnell ally has even been advising a candidate who wants to primary Brooks next year for his congressional seat. The negative ads seem to be working given that Brooks, despite being close, hasn’t gotten into either first or second place in any public poll.

The effectiveness of these anti-Brooks ads can also be seen in the type of voter who is backing him. You’d expect Brooks to be well liked among conservative voters. He has a very conservative record in Congress, is a member of the Freedom Caucus, has the backing of Sean Hannity and has courted conservative outside groups during the campaign. Yet the JMC Analytics and Polling survey showed he’s running weakest among self-described “very conservative” primary voters. The Red Racing Horses survey also showed Brooks in a distant third place among those who approve of the job Trump is doing as president, while in first place among the much smaller group of Republicans who don’t approve of the job Trump is doing.

Whomever emerges next Tuesday will have more than a month to fight it out. There’s been very little runoff polling, and it’s not entirely clear what might happen. The good news for the Republican who emerges from that skirmish is he will be a heavy favorite in December’s general election in deep-red Alabama.