A U.S.-backed U.N. Security Council resolution authorizing war against Iraq appears doomed to fail, senior U.S. officials and foreign diplomats said today, though the Bush administration agreed to a British request to continue negotiations until Monday before calling for a vote or withdrawing the measure.

U.S. officials in recent days have claimed, without providing evidence, that they were within striking distance of reaching the necessary nine votes on the deeply divided Security Council. But officials were noticeably gloomy today after a British compromise offered Wednesday was largely rejected by the six countries that are officially undecided.

In addition to an almost certain French veto, and the possibility of a Russian veto, officials said they were convinced they would not even achieve what they call the "moral victory" of nine votes among the council's 15 member nations.

"It looks pretty grim," one senior administration official said. Another senior U.S. official said: "There is no reason to believe positions will change today or tomorrow."

The apparent defeat of the resolution would be a stunning diplomatic setback for President Bush and his closest partner, British Prime Minister Tony Blair. U.S. officials have made it clear that they only agreed to pursue a second resolution at the request of Blair, who needed the imprimatur of the Security Council for a war against Iraq to shore up political support at home. But the failure to win all but a handful of votes for military action is an unusually public rebuff of the United States.

Diplomatic tension ran high today, as U.S. and British officials assailed what they considered high-handed intransigence on the part of France, which rejected the British proposal even before Iraqi officials did so in Baghdad. Jeremy Greenstock, Britain's ambassador to the United Nations, appeared wan and haggard as he attempted to gather support for a compromise that would lay out conditions for Iraqi President Saddam Hussein to meet to avoid a war.

But diplomats said the U.S. insistence that Hussein be given only until next week to disarm was too much and too fast for the other countries on the council. "A lot of us feel bad about doing Saddam's bidding but that appears no worse than carrying out a war for the Americans," said a diplomat from one of the undecided nations.

Though administration officials rejected proposals from the undecided nations to let weapons inspectors continue for a few more weeks, Marine Gen. Peter Pace, the vice chairman of the Joint Chiefs of Staff, told military experts at the Pentagon today that a delay of a month or more in invading Iraq could easily be dealt with by the military and would not increase American casualties.

White House officials said they are proceeding with plans for Bush to address the nation once the diplomatic process is over. The speech would include a final "ultimatum to avoid war" to Hussein, and would serve as the signal for international officials, foreign diplomats and journalists who might choose to evacuate Iraq that war is imminent.

U.S. officials also began laying the groundwork today for Bush to reverse his pledge to call for a Security Council vote, no matter how bad the vote count looked, because "it's time for people to show their cards." Under one scenario, the administration could say the resolution was being withdrawn at the request of the co-sponsors, Britain and Spain.

Secretary of State Colin L. Powell told lawmakers on Capitol Hill today: "The options remain go for a vote and see what members say, or not go for a vote. But all the options that you can imagine are before us and we will be examining that today, tomorrow and over the weekend."

White House spokesman Ari Fleischer sidestepped questions about whether Bush would still call for a vote. "Your premise is suggesting that in the conducting of diplomacy there can be no room for flexibility," he told reporters. "And as the president travels the last bit of this road, he is going to work to consult with our allies and friends."

Bush did not attend a St. Patrick's Day luncheon on Capitol Hill so he could take an urgent phone call from Blair, who asked for several more days to make the case to Security Council members after defeat appeared certain in a vote that had been scheduled for Friday, a senior administration official said.

Due to face Parliament on the Iraq question Tuesday, Blair hopes that delaying what appears to be inevitable defeat until Monday will enable him to tell the House of Commons that he made the maximum negotiating effort. "He's got a big day in Parliament on Tuesday," the U.S. official said. "He didn't want either a vote or a withdrawal of the resolution to happen today or tomorrow."

Unlike the Bush administration, British officials said that they are not resigned to defeat and that Bush and Blair will continue intensive telephone diplomacy this weekend as they try to persuade at least five of six publicly uncommitted council members to vote for the measure. "We wouldn't waste the president and the prime minister's time this weekend if we didn't think it was worth it," a British official said.

Still, another British official conceded, "We aren't there yet, and I can't say we will get there. We are asking people to take a hard decision, and quite a lot of people want to have clean hands and leave hard decisions to others."

In a rare moment of levity at a tense closed-door Security Council session Wednesday night to discuss the British compromise, one participant said the Guinean ambassador, who is council president this month, remarked about the British compromise: "It was better to have a bad document than no document at all."

The British resolution, co-sponsored by the United States and Spain and also supported by Bulgaria, needs nine of the 15 council votes for passage, and no veto by any of the five permanent members. Two permanent members, France and Russia, have indicated they would veto the measure, and France repeated that even a revised version was "unacceptable."

In the face of likely vetoes, Britain and the United States have been struggling to secure the nine votes. To get there, they need at least five of the six uncommitted members -- Guinea, Angola, Cameroon, Chile, Mexico and Pakistan -- to add to the four original supporters.

In addition to France and Russia, Germany, Syria and China, which also is a permanent council member, have indicated they will not vote for the resolution. Although final decisions are now likely to be put off until Monday, Chile and Mexico were expected to tell Britain that they will not support the measure.

U.S. and British officials believe that the French veto promise has made it easier for uncommitted governments to turn against the resolution since it has no chance of passage. All of them, particularly the Latin American nations and Pakistan, face widespread antiwar pressure at home.

In Baghdad, Foreign Minister Naji Sabri rejected the British compromise outright. "It is a dressing up of a rejected proposal, an aggressive plan for war," he said.

DeYoung reported from Washington.