Nancy Pelosi, who has led Democrats in the US House of Representatives for almost two decades, has announced she is standing down from the role.
The 82-year-old is the most powerful Democrat in Congress and the first woman to serve as speaker of the House.
She will continue to represent her California district in the lower chamber of Congress.
It comes as Republicans are projected to take back control of the House following the midterm elections.
Republican Kevin McCarthy has won the party’s nomination to be speaker in the new Congress and is likely to succeed Mrs Pelosi.
“I never would have thought that someday I would go from homemaker to House speaker,” Mrs Pelosi said in a statement in the chamber on Thursday.
“I will not seek re-election to Democratic leadership in the next Congress. The hour has come for a new generation to lead the Democratic caucus,” she said.
Mrs Pelosi will serve as speaker until January when a new Congress takes over, and will remain in the seat she first took up in 1987 until January 2025.