US Senate Republican leader Mitch McConnell said on Wednesday he will step down from his leadership role, leaving a power vacuum atop the party he has piloted for nearly 17 years, more than any other party leader in the chamber's history.

"I turned 82 last week. The end of my contributions are closer than I prefer," McConnell said on the Senate floor, his voice breaking with emotion. "Father Time remains undefeated. I'm no longer the young man sitting in the back hoping colleagues remember my name. It's time for the next generation of leadership."

The 82-year-old Kentucky lawmaker played an outsized role in helping former President Donald Trump cement a 6-3 conservative majority in the Supreme Court, paving the way for landmark rulings cheered by conservatives ending the recognition of a constitutional right to abortion and expanding gun rights.

That belied McConnell's personal opposition to Trump at times – particularly Trump's conduct ahead of the January 6, 2021, attack on the US Capitol – as well as McConnell's continued vocal support for trying to pass aid to Ukraine in its fight against a Russian attack over the opposition of hardline Republican opponents.

Democrats hold a slim majority in the Senate, with McConnell now serving as minority leader after previously holding the post of majority leader. McConnell said he will not run for Senate Republican leader in November's party elections, meaning he will end his time as leader when a new Congress convenes in January.

McConnell's departure from the leadership will remove a central character in negotiations with Democrats and the White House on spending deals to keep the federal government funded and avert a shutdown.

His steady command of his caucus stood in contrast to relatively newly minted Republican House of Representatives Speaker Mike Johnson, who has struggled to lead his thin majority.

McConnell twice last summer froze up while making remarks in public, raising questions about his ability to continue to carry out the duties of his high-powered job. Those concerns were not assuaged by an August 31 note from the congressional physician that cleared McConnell to go on working. (Reuters)