John Boehner, House Speaker, Will Resign from Congress

Mr. Boehner, 65, made the announcement in an emotional meeting with his fellow Republicans on Friday as lawmakers struggled to avert a government shutdown next week, a possibility made less likely by his decision.

Mr. Boehner told almost no one of his decision before making it. “So before I went to sleep last night, I told my wife, ‘You know, I might just make an announcement tomorrow,’ ” Mr. Boehner said at a news conference in the Capitol. “This morning I woke up, said my prayers, as I always do, and thought, ‘This is the day I am going to do this,’ The New York Times reported.

His downfall again highlighted the sinewy power of a Republican Party faction whose anthem is often to oppose government action. It also made vivid the increasingly precarious nature of a job in which the will and proclivities of a politically divisive body must be managed. No House speaker since Thomas P. O’Neill Jr., who held the gavel from 1977 to 1986, has left the job willingly.

For Mr. Boehner, who has been pressured throughout his tenure to push for deeper spending cuts and more aggressive policy changes than were possible with President Obama in the White House, seemed both exhausted by the fight and yet at peace with his final move: to leave rather than face a potentially humiliating fight within his party.

“My first job as speaker is to protect the institution,” Mr. Boehner said. “It had become clear to me that this prolonged leadership turmoil would do irreparable harm to the institution.”

Mr. Boehner said he would leave at the end of October. The leading candidate to replace him is Representative Kevin McCarthy of California, the majority leader, who is viewed more favorably by the House’s more conservative members both for his willingness to bend to their will and for his cheerful manner.