Jeff Sessions formally announced on Thursday that he was entering the Senate race in Alabama, a decision that will likely put him on a collision course with President Trump, who still harbors resentment toward the former attorney general a year after forcing him from office.
In a statement issued just after 8 p.m., Mr. Sessions took pains to signal that he had remained loyal to the president despite their differences. “When I left President Trump’s cabinet, did I write a tell-all book? No. Did I go on CNN and attack the president. No. Have I said a cross word about President Trump? No,” the statement said. “I was his strongest advocate. I still am. We must make America great again.”
The announcement came after several weeks of public leaks and private maneuvering during which the former attorney general tested the waters about running for what would be his fifth term in the Senate. He gave up his seat in 2017 after Mr. Trump nominated him and the Senate confirmed him.
But their relationship soon soured as Mr. Sessions, an adviser to Mr. Trump’s first presidential campaign, decided to recuse himself from overseeing the Justice Department’s investigation into whether Mr. Trump and his associates worked illegally with Russians to interfere in the 2016 election. Mr. Trump has never forgiven Mr. Sessions, who was the first member of the Senate to endorse his presidential bid.
Because Mr. Trump has an almost imperial hold on the Republican Party, Mr. Trump’s dislike could make for a rough road ahead for Mr. Sessions. Republicans who find themselves in Mr. Trump’s political cross hairs rarely fare well with their party’s voters. And the president has sent word to the former attorney general through allies that he would publicly attack him if he went ahead with the campaign.
But Mr. Sessions has been an admired figure in Alabama Republican politics for four decades and, by many accounts, remains popular there despite the withering scorn Mr. Trump has leveled at him. Among other insults, Mr. Trump has accused Mr. Sessions of betrayal and of being a “total joke” of a leader at the Justice Department. More recently, the president has referred to him as a “jerk” in private conversations.
Mr. Sessions did not undertake the decision to run again lightly. He sought out advice on the race from dozens of friends and associates in Alabama, Washington and beyond in recent weeks. He commissioned polling to test how strong a contender he would be in a Republican primary that is already quite crowded with well known names. The numbers came back indicating that the race was winnable, according to one person who is close to him.
Alabama Republicans have a history of voting their will — regardless of what Mr. Trump tells them to do. Two years ago during the special election to fill Mr. Sessions’s old seat, Mr. Trump endorsed Luther Strange, the Republican leadership’s preferred candidate. Mr. Strange lost the primary to Roy S. Moore, the former state chief judge who has a large following among religious conservatives there.
In the general election, Mr. Trump endorsed Mr. Moore and stood by him even after several women came forward to say that the judge had touched them inappropriately when they were teenagers. Mr. Moore lost the race to Senator Doug Jones, who is the first Democrat to represent Alabama in the Senate in a generation.
The prospect of another divisive Republican primary is making many Republicans nervous that Mr. Jones could be re-elected, which would imperil the party’s ability to keep its Senate majority. Mr. Moore is running again and announced his bid in June. Two other candidates also appear to be formidable: Representative Bradley Byrne, whose district is near Mobile; and Tommy Tuberville, the former Auburn University football coach.