Prime Minister Tony Blair of Britain braced for a rebellion this week from within his own government and Labor Party over the apparent, imminent failure of his diplomatic efforts on Iraq, which threatens to wound him politically and leave him counting on a quick, successful war to revive his standing.

The Azores summit, called in large part to help Blair with his domestic crisis, offered him 24 hours of relief as he said he would make one last effort to procure wider international support for a war to force the Iraqi government to disarm.

But the British government has virtually given up hope of winning a new U.N. Security Council resolution endorsing the use of force in Iraq, according to officials and political commentators. Blair has been spearheading the campaign to get such a resolution, which is crucial for him in gaining the support of Labor's left wing and in rallying domestic public opinion for planned British participation in a U.S.-led war.

The costs to Blair are likely to include the resignations of one or two cabinet ministers and several lower-ranking government officials, and an increase in opposition to his policy among Labor members of Parliament. A vote over his pro-American position on the Iraq crisis could come early this week.

Blair is assured of securing enough votes to stay in power, partly because the opposition Conservative Party supports his policy of joining the United States in a war against Iraq. Britain has committed about 45,000 troops to the Persian Gulf region in anticipation of the conflict.

"Although he will have a great uproar in the House of Commons, if there is a vote, he will survive it," said Robert Worcester, chairman of MORI Research, a polling organization in London.

Moreover, there have been signs this week of a modest shift in Blair's favor, owing partly to satisfaction with his intense campaign to press the Bush administration to make every possible effort to get U.N. support for a war. The result at the Azores summit, by seeking to emphasize there was one last chance for diplomacy, could help Blair further.

"It's more or less a lost cause, but it could give the impression of going the last mile, of bending over backward for peace. It might help him with his own party," said Paul Rogers, a professor of peace studies at the University of Bradford.

Another factor helping Blair has been a backlash in Britain against France's threat to veto a new U.N. resolution. Seventy percent of Britons surveyed oppose France's position, according to a YouGov poll conducted for ITV1 television.

"I think the landscape has changed," Peter Bradley, a Parliament member who was considering resigning a week ago, told the Sunday Times. "I and others have realized that the French posturing for peace has made diplomacy impossible and war almost inevitable."

Still, the YouGov poll also found that 65 percent of Britons oppose a war without a new Security Council resolution. That is down from 73 percent in late January but is still a formidable headache for Blair.

Graham Allen, a Labor member of Parliament who has helped lead the opposition to Blair, said he hoped "nobody believes" that what Blair called "a final round of contacts" on the diplomatic front on Monday would make a difference.

"We're going to war. Tomorrow is window-dressing day. Let's blame the French, the Germans, the Russians, anybody at all apart from the man who set the timetable, George W. Bush," Allen said.

One of the biggest blows to Blair could be the resignation of Robin Cook, who as leader of the Commons is a member of the cabinet. He is a respected figure and previously was Blair's foreign secretary. Sources close to Cook were quoted in several British papers as saying he would step down if Britain went to war without U.N. backing.

The other cabinet-level official who may resign is International Development Secretary Clare Short, who sparked a major controversy a week ago by labeling Blair's policy "reckless."

If war begins, many political commentators predict that Blair would benefit for a time from a patriotic surge of support for British troops.

"When Tommy goes to war, as it looks like Tommy is going to war, British public opinion will swing behind him," Worcester said, employing the nickname for the British soldier.

In that event, Blair's political fortunes would rest on how the conflict proceeded, and especially whether it were prolonged.

"What we do not know is how people will react beyond the onset of the war, bearing in mind that first two days will be of an intensity that has not been seen previously," Rogers said, referring to reports that the initial assault will be particularly large and aggressive. "If the war did not go according to plan, with heavy civilian casualties, then there may be a challenge to his leadership from within the party," Rogers said.

British Prime Minister Tony Blair studies papers on his flight to the Azores summit, which was held in part to convince Parliament and British citizens that Blair was making every effort to win wider international support for use of force against Iraq if diplomacy failed to achieve disarmament.