Byrne hit both rivals in an ad, Tuberville responded by attacking the other two over their support for Trump and Sessions released a late ad bashing the former football coach.

“That tells me that their internal data shows that they're all three as close as can be, and it’s a toss-up as to which two will make the runoff,” said Rep. Mo Brooks (R-Ala.).

Whether the former attorney general faces Tuberville, who is second in most polls, or Byrne, who has run the most aggressive campaign on the ground, Sessions will be in a four-week dogfight for the likely March 31 runoff. One veteran GOP operative in the state, who requested anonymity to speak frankly, said it should concern Sessions if he finishes in the low-30-percent range Tuesday, where he has been in recent polling — but that low-to-mid-40 percent showing would be more promising.

“For all intents and purposes, he is an incumbent in Alabama. He's been on the ballot since 1994,” the operative said. “The guy is as known as you can be known as a politician. So, inside a Republican primary, I'm worried that there is that sentiment out there that, 'He didn't stand with the president, and I'm going to vote for somebody other than Jeff.'"

Sessions’ surprise announcement in November that he was seeking his former seat scrambled the race to face Jones, chasing out a top-tier candidate and relegating others — including Roy Moore, the controversial former judge whom Jones defeated in a 2017 special election after Sessions resigned — to also-ran status. But Byrne and Tuberville, who stayed in the race after Sessions' entry, have fought it out over the recent months to get a one-on-one shot at the former attorney general.

Despite the end of Sessions' tenure in the Trump administration, he has taken pains to remind Alabama voters about his longtime service and his early endorsement of the president, focusing on it during his announcement in November and his closing TV ad in the race last week.

“Others talk big about Trump, hoping to get your vote. But talk is cheap,” Sessions said in the ad. “I’ve been with him from the start because it’s the right thing for America.”

But as he’s emphasized his support for Trump, Sessions' rivals have repeatedly hit Sessions for his recusal from the investigation into Russian interference in the 2016 election that led to the appointment of a special counsel and his dismissal from the cabinet. Tuberville ran an ad saying Sessions “deserted President Trump,” and a Byrne spot simulated a job interview in which an actor said Sessions “let the president down and got fired.”