WASHINGTON — Republican Sen. Mitch McConnell announced on Thursday that he won’t seek reelection next year, ending decades of 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 addressed colleagues Thursday 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.”

His announcement begins 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 other senators soon did so as well.

Sen. Lindsey Graham of South Carolina 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 he froze while 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.

McConnell’s looming departure reflects the changing dynamics of the Trump-led GOP. McConnell has seen his power diminish on a parallel track with both his health and his relationship with Trump, who once praised him as a key ally but has taken to criticizing him in caustic terms.

In Kentucky, McConnell’s departure will mark the loss of a powerful advocate and will set off a competitive GOP primary next year for what will now be an open Senate seat.

Kentucky Democratic Gov. Andy Beshear, seen as a rising star in his party for winning statewide office in Republican territory, has said he has no interest in the Senate.