Mitch McConnell, the Republican leader of the US Senate, will stand down in November.
It ends a record run in the powerful post, that has seen the 82-year-old trade blows with many top figures in multiple US administrations of the last two decades.
In remarks made in the Capitol Building, Mr McConnell said: “One of life’s most underappreciated talents is to know when it’s time to move on to life’s next chapter.
“So I stand before you today… to say that this will be my last term as Republican leader of the Senate.”
Despite relinquishing the position of Senate leader, Mr McConnell intends to see out his term in the US’ upper house, which ends in January 2027.
Born in 1942, the former attorney has represented Kentucky in the chamber since 1985.
He was first named party leader for the GOP in 2007, and has since won nine successive elections to keep the post for 17 years – the longest anyone has led their party in the Senate in US history.
The Kentucky senator also said: “I love the Senate. It has been my life.
“There may be more distinguished members of this body throughout our history, but I doubt there are any with more admiration for it.
“Father Time remains undefeated. I am no longer the young man sitting in the back, hoping colleagues would remember my name. It is time for the next generation of leadership.”
Questions were raised about his fitness for office last year after a number of public instances where he appeared to freeze while speaking.
In July, the Republican appeared to stop mid-sentence and stare into space for around 20 seconds while giving a weekly press conference.
His Republican colleagues grabbed his elbows and asked if he wanted to go back to his office after pausing, before he slowly walked back with an aide and the senator for Wyoming, John Barrasso.
Then, in August, Mr McConnell appeared to freeze again when asked if he would run for re-election.
After being asked the question, he stopped speaking and stared for more than 30 seconds, before being asked: “Did you hear the question, senator?”
He did come around and briefly respond to another question.
Those moments came after Mr McConnell was out of the Senate for almost six weeks that March, when he fell and hit his head at a dinner event.
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