“It's like he's holding his lead and playing prevent defense,” Chris Brown, a GOP strategist in the state who raised concerns about Tuberville’s lack of vetting in the primary, said, invoking a football metaphor for extreme cautiousness. “I don't think people really know much about Tommy Tuberville other than Trump endorsed him, and he coached football.”

In Alabama, that may prove to be enough. The two men are vying to take on Sen. Doug Jones, who won a special election in 2017 and is the most vulnerable Democrat up this year. As Trump and his party have seen their poll numbers slip over the past few months, a victory in Alabama is essential to Republicans' chances of retaining their Senate majority.

Instead of the pending matchup with Jones, the runoff has been defined by Trump's continued ridicule of Sessions, who held the Senate seat for two decades before Trump plucked him out of the chamber to take over the Justice Department. But Sessions' recusal from the investigation over Russian meddling in the 2016 presidential election, while praised by career prosecutors and ethics watchdogs, drew Trump's ire — and Sessions never recovered in the president's eyes.

"Jeff Sessions is a disaster who has let us all down," Trump tweeted on Saturday, three days before Tuesday's runoff. "We don't want him back in Washington!"

Sessions fired back, calling the insults "juvenile" and reiterating his opinion that Tuberville was "too cowardly" to debate.

Trump went after Sessions again Monday evening on a call with Tuberville and supporters of the football coach.

Trump called Tuberville a "true conservative" and a "really successful coach" and reiterated his endorsement. He also took Sessions to task once again. "I will tell you I got to know Jeff Sessions very well. I made a mistake when I put him in as the attorney general," Trump said. "He had his chance and he blew it."

After Tuberville narrowly edged out Sessions for first place in the March 3 primary, the runoff originally scheduled for the final day of March was postponed until mid-July. The change sapped Tuberville of the momentum from his primary victory and Trump’s endorsement a week later. It has also created an uncertain turnout environment, with several other competitive runoffs lower on the ballot. Low turnout could benefit Sessions, who's been involved in the state's politics for decades.

But while that time gave Sessions opportunities to reinvigorate his campaign, it hasn’t necessarily changed the outlook of the race. Polls have shown Tuberville with a lead and he secured the endorsement of Will Ainsworth, the state’s lieutenant governor, last week.

“Coach Tuberville will whip Doug Jones,” Ainsworth said in an interview. “Doug Jones is an out-of-touch liberal — that does not resonate with Alabama. That was a fluke.”

Tuberville has defended his strategy, likening debating Sessions at this point in the campaign to "punting on first down" in a radio interview last month. He’s also battered Sessions in TV ads, throwing back the “weak” accusation and attacking Sessions for his deteriorated relationship with Trump.

Still, some Republicans have been frustrated by the lack of engagement during four-month runoff. Rep. Gary Palmer, who considered running for Senate, said in a recent local radio interview it bothered him there hadn’t been a debate. Some Republican consultants not affiliated in the race have expressed concern about what’s waiting for Tuberville if he emerges Tuesday — pointing to a recent New York Times report about Tuberville's involvement in a failed hedge fund for which his associate pleaded guilty to fraud.

“Because he has not been vetted, because this is his first campaign and because Doug Jones is sitting on millions and millions of dollars, there is concern over whether Tommy Tuberville will be able to survive the type of campaign Doug Jones is going to run,” said Angi Stalnaker, a veteran operative who was a top aide to former Gov. Robert Bentley. “We don't know anything about Tommy Tuberville other than he is a football coach and loves Donald Trump. And we're all keeping our fingers crossed that's going to be enough to take back that seat for Republicans.”

Trump carried Alabama by nearly 30 percentage points in 2016, and most Republicans believe either man will defeat Jones — who won in the 2017 special election by less than 2 percentage points over Roy Moore, who had been accused of inappropriate sexual behavior with minors.

But the GOP is still planning to spend precious resources to win. The Club for Growth, which endorsed Tuberville after Trump did, is launching $1.3 million in TV ads the morning after the runoff. One Nation, a dark-money group affiliated with Majority Leader Mitch McConnell, is neutral in the primary but booked $3.2 million to air starting the following week.

“The fight in Alabama will continue, I predict, the day after the runoff and go all the way through November,” David McIntosh, the Club for Growth president, said in an interview.

A poll conducted for the Club for Growth from June 29-July 2 found Tuberville with a double digit lead over Jones, 50 percent to 40 percent.

Democratic polling has shown a narrower race. An internal survey for Jones campaign conducted in May and released in mid June showed Jones trailing Tuberville by 3 percentage points. And an independent survey from ALG Research, an Alabama-based Democratic firm, showed Jones trailing Tuberville by 3 points and Sessions by 2 points.

Sessions has repeatedly been on the attack during the runoff, in the unfamiliar spot of insurgent candidate running from behind without the benefits of incumbency. He has called Tuberville weak for not debating, and said he would be ineffective in the Senate. He has posted his local media interviews on Twitter while criticizing Tuberville, an Arkansas native who spent a decade as the head coach at Auburn University, for not talking to press.

“Jeff Sessions is tough, and he's determined, and he's really bright. So he's been focused for the last few months on winning every day,” said Curt Anderson, a top adviser to Sessions’ campaign. “Tuberville has basically been on autopilot and figured the Trump endorsement is all he needs, and he'll be fine. Which could be true, by the way. But Sessions has really been battling and talking about issues at length.”

Tuberville’s campaign declined to make him available for an interview and did not respond to written questions submitted by POLITICO. But his allies brushed aside Sessions' attacks as merely swings from a candidate badly trailing.

“I think Jeff Sessions is in trouble, and he knows it, and he's just grasping for straws,” said Ainsworth, the lieutenant governor who endorsed Tuberville.

Jones' campaign hasn’t weighed in or aimed to lift one of his potential opponents. Instead, he has spent nearly $1.4 million on TV with a series of positive ads speaking directly to camera about his record and issues in the race.

Joe Trippi, a senior adviser to Jones, pointed to the internal polling showing them narrowly trailing either Republican.

“We're in a dead heat and have $8 million in the bank against somebody who has a divided party and is going to have to re-up the money,” Trippi said. “We feel pretty good about our chances. Right now, we're running on our record.”