WASHINGTON — Republican Sen. Mitch McConnell announced Thursday that he won’t seek reelection next year, ending a decadeslong tenure as a power broker who championed conservative causes but ultimately ceded ground to the fierce GOP populism of President Donald Trump.

McConnell, the longest-serving Senate party leader in U.S. history, chose his 83rd birthday to share his decision not to run for another term in Kentucky and to retire when his current term ends. He informed The Associated Press of his decision before he addressed colleagues in a speech on the Senate floor.

“Seven times, my fellow Kentuckians have sent me to the Senate,” McConnell said, as aides lined the back chamber and senators listened from seats. “Every day in between I’ve been humbled by the trust they’ve placed in me to do their business right here. Representing our commonwealth has been the honor of a lifetime. I will not seek this honor an eighth time. My current term in the Senate will be my last.”

The scramble for McConnell’s seat intensified soon after McConnell spoke.

Former state Attorney General Daniel Cameron, a Republican, said he’s in the race to succeed his one-time mentor, having formerly worked as McConnell’s legal counsel. Cameron lost the 2023 governor’s race to Democratic incumbent Andy Beshear but has been planning a political comeback. Cameron said Thursday that his values align with Kentucky voters and touted his support for Trump.

“I’m going to be an ‘America First’ senator and it’s time for a new generation of leadership,” Cameron told the AP in a phone interview Thursday evening.

McConnell’s retirement announcement began the epilogue of a storied career as a master strategist, one in which he helped forge a conservative Supreme Court and steered the Senate through tax cuts, presidential impeachment trials and fierce political fights. Yet with his powerful perch atop committees, and nearly two years remaining in his term, McConnell vowed to complete his work on several remaining fronts.

“I have some unfinished business to attend to,” he said.

McConnell walked gingerly to the podium, sporting a walking boot. Senators from both sides of the political aisle seemed to listen most intently as he told them that while there are any number of reasons for pessimism, the strength of the Senate is not one of them.

“The Senate is still equipped for work of great consequence,” he told them.

As he concluded, Sen. Thom Tillis, R-N.C., motioned for the audience of senators, staff and Capitol visitors be allowed to applaud, which is usually not allowed under Senate rules.

Republican senators then lined up to greet McConnell, beginning with Sen. Susan Collins of Maine, who hugged him, and Sen. Lisa Murkowski of Alaska, who patted him on the back. He took out a tissue and made a joke, prompting the group to laugh. Senate Majority Leader John Thune of South Dakota gave him a warm handshake, and a dozen others senators soon did so as well.

Sen. Lindsey Graham said McConnell reshaped the American judiciary, particularly the Supreme Court. “He has a lot to be proud of, and I am sure he will work hard to the very end of his term,” Graham said.

McConnell, first elected in 1984, intends to serve until his term ends in January 2027. The Kentuckian has dealt with a series of medical episodes in recent years, including injuries sustained from falls and times when his face briefly froze while he was speaking.

The famously taciturn McConnell revered the Senate as a young intern long before joining its back benches as a freshman lawmaker in the mid-1980s. His dramatic announcement comes almost a year after his decision to relinquish his leadership post after the November 2024 election.