Sessions, 72, must decide within days whether to run: Candidates have until Nov. 8 to qualify for the ballot.

Five Republicans are already in the race: Rep. Bradley Byrne, former Auburn University football coach Tommy Tuberville, Secretary of State John Merrill, state Rep. Arnold Mooney and Roy Moore, the former state Supreme Court judge who lost the special election in 2017 amid allegations of sexual misconduct.

Sessions has some high-profile allies pushing him to run for his old seat, including the conservative Club for Growth.

“We are hearing that Sessions is seriously considering running for Senate again and that polling indicates he would be in very good shape. The Club for Growth has in the past and would once again encourage him to run for that Senate seat,” David McIntosh, the organization’s president, told POLITICO.

“We were enthusiastic way back early on that Sessions, when he retired from the attorney general spot, might go back to the Senate,” McIntosh added. “At that point, he didn't want to think about that because he was just finishing up one job. I'm very encouraged he's now seriously considering it."

A Sessions comeback would face steep hurdles — chiefly, assuming he hasn't had a change of heart, the president. Trump castigated Sessions throughout most of his tenure, and a reprise of his Twitter assaults could quickly make a primary campaign untenable.

“There isn’t anyone who has fallen more out of favor with President Trump than Jeff Sessions. Whatever goodwill that might still exist for him among Alabama Republicans would evaporate after sustained Trump tweets," said one Republican steeped in the race who is unaffiliated with a candidate.

The Russian Witch Hunt Hoax continues, all because Jeff Sessions didn’t tell me he was going to recuse himself...I would have quickly picked someone else. So much time and money wasted, so many lives ruined...and Sessions knew better than most that there was No Collusion! — Donald J. Trump (@realDonaldTrump) June 5, 2018

But McIntosh said he believes Sessions could overcome any potential resistance from the president because of his history as Trump’s top ally in the Senate during the 2016 campaign.

“I think he'd see his role in the Senate as pushing Senate Republicans to actually enact the Trump agenda,” McIntosh said.

A person familiar with Sessions thinking declined to comment for this story.

Sessions declined to discuss whether he would get in last month when he was spotted near the Capitol. If he were to regain his old Senate seat, he'd likely lose his prior seniority in the chamber.

Sessions would immediately have the money to compete in the primary. He still has $2.5 million in his campaign account, according to the most recent Federal Election Commission filing. Only Byrne has more money in the bank, with slightly over $2.5 million cash on hand. Tuberville is next closest with $1.5 million.

Republicans view Alabama as their best opportunity to pick up a Senate seat in 2020 as they seek to retain their majority. Recent polling has shown Tuberville with a lead among the GOP field, though the race remains wide open. The primary is in early March, and if no candidate tops 50 percent, the top two finishers compete in a runoff at the end of March.