London ? Prime Minister Tony Blair, his reputation in Britain badly damaged by his refusal to break ranks with President Bush, gave in Thursday to a fierce revolt in his Labour Party and reluctantly promised to quit within a year.

Blair, whose popularity began sinking when he committed his nation to the U.S.-led war in Iraq three years ago, had long resisted calls to publicly set a timeframe for his departure from office. He feared such an announcement would make him a lame duck and sap his remaining authority.

But ultimately, the foreign leader best known to Americans could find no other way to end days of public turmoil that were severely damaging Labour, which has been in power for nearly a decade but now trails the opposition Conservatives in the polls.

“I would have preferred to do this in my own way,” Blair said, as he conceded that the party’s annual conference this month would be his last. Next year’s conference is scheduled for September 2007.

He refused to set a specific departure date, saying, “The precise timetable has to be left to me and has to be done in the proper way.”

Blair appeared to have struck a deal with his expected successor, Treasury chief Gordon Brown, who signaled his support in a statement minutes before Blair spoke to television cameras at a north London school.

The key question is whether the prime minister’s exit strategy will be detailed and speedy enough to satisfy the impatient Labour legislators who forced his hand.

Early signals were that it would buy the 53-year-old Blair time – but not much. He’s eager to reach the 10-year anniversary of his 1997 assumption of office, which would be in May.

White House spokesman Tony Snow said Blair and Bush still had a lot of work to do together.

“He’s a valued ally,” Snow said. “And at this point, we’re not sitting around writing encomia for Tony Blair. We’re instead busy working with him.”

With the outbreak of the Iraq war in 2003, Blair began to lose the iron control he once exercised over his party.

Long derided by critics as the U.S. president’s “poodle,” he suffered a further blow at July’s G-8 summit in St. Petersburg, Russia. An open microphone caught a chat in which he seemed embarrassingly subservient to Bush, who greeted him by shouting “Yo, Blair!”

Anger over his handling of this summer’s Mideast fighting and anxiety over the party’s slide in the polls fueled the rank-and-file’s impatience for him to leave quickly, or at least to say when he planned to go. Blair’s refusal to call for an early end to the Israel-Hezbollah fighting in Lebanon was the final provocation for many once-loyal supporters.

It served as yet another reminder of his close alliance with Bush – a friendship widely detested within the Labour Party – and stirred bitter memories of Blair’s decision to commit Britain to the Iraq war despite intense public opposition.

That conflict is the root of his political problems, and continued bloodshed in Iraq keeps it in the headlines. The war has severely damaged his credibility and was widely seen as the reason Labour suffered a sharply reduced majority when he led it to a third straight election win last year.

Blair promised before that vote that he would not seek a fourth term.

A resurgent Conservative Party with a dynamic young leader, David Cameron, has added recently to his woes.

Cameron, benefiting from Labour’s troubles, said the government was at war with itself.

“What’s happened today isn’t going to end the uncertainty,” he said in a statement. “It will probably only add to the paralysis. And frankly Britain deserves better than this.”

British governments usually serve maximum five-year terms before the House of Commons must face re-election. The prime minister is almost always the leader of the party that commands a parliamentary majority.

But an election can happen more quickly – either because the prime minister loses majority support in the Commons, or chooses to call an early election in hopes of increasing the government’s majority. If a prime minister resigns or dies, an election is not required; the new leader of the governing party can become prime minister if backed by a Commons majority.