Democrat Joe Manchins plans to resign from the U.N. General Assembly on Monday, his office said.
The announcement comes as the Senate prepares to vote on a sweeping health care bill.
The Manchin announcement comes after several weeks of speculation that he could resign to push for the legislation, which would repeal and replace the Affordable Care Act.
Manchin said in a statement that he plans to “make this decision with great pride, dignity and respect for all Americans.”
“I am committed to continuing to advocate for the health and wellbeing of our people in Congress and across our country,” Manchin said.
Manchins announcement comes amid mounting speculation that the retiring senator could retire to run for a U.K. parliament seat.
He would face a hard battle to win the seat, which is expected to be held by Labour Party leader Jeremy Corbyn.
The U.B.I. said last week that Manchin had agreed to resign in exchange for a job as an ambassador at the U,S.
Embassy in London.