WASHINGTON -- Losing their U.N. fight, President Bush, British Prime Minister Tony Blair and Spanish Prime Minister Jose Maria Aznar agreed Friday to take a last-ditch stab at reviving their troubled war resolution at an Atlantic island summit.

Billed as a bid "to pursue every last bit of diplomacy," the Sunday session was hurriedly scheduled amid a cascade of events -- all pointing to war, perhaps just days away.

U.S. warships steamed into the Red Sea within cruise missile range of Iraq. A prominent Muslim cleric urged Iraqis around the world to target American interests and "set them ablaze." Thousands of anti-war demonstrators gathered in Washington for a weekend march on the White House.

Inside the wrought-iron gates of the presidential mansion, Bush's team quickly rejected the latest bid for a diplomatic compromise at the United Nations. "It's a nonstarter," White House spokesman Ari Fleischer said of Chile's plan to give Iraq a three-week deadline to comply with new conditions.

On the eve of U.S. protests, millions of workers staged anti-war demonstrations in Spain. Aznar compared opponents of war to the appeasers of Adolf Hitler.

"Not acting to rid the world of weapons of mass destruction is neither politically nor morally acceptable," the Spanish leader said. Blair, under fire for backing Bush on Iraq, welcomed both the summit and a new U.S. push for Middle East peace.

While announcing the summit, Fleischer renewed a long-standing U.S. threat to disarm Iraq, with force if necessary, even if the United Nations does not back military action. The Security Council voted 15-0 in November to demand that Iraq disarm or face "serious consequences."

Blair's urging

At Blair's urging, Bush agreed to pursue a second resolution and said he would put it to a vote, even if the measure was doomed to fail.

As he backpedaled on that, White House officials hastily organized the summit in the Azores, islands that are part of Portugal and a traditional eastern-Atlantic refueling stop.

National Security Adviser Condoleezza Rice said the leaders will explore "all of the possibilities," a signal that the summit agenda will include talk about waging war without U.N. approval. "It is time to come to a conclusion that says to Saddam Hussein, it is time for you to disarm or be disarmed," she said.

Fleischer said Bush will "discuss the importance of pursuing every last bit of diplomacy, to work toward passage of a Security Council resolution."

However, administration officials said there was little chance of changing opponents' minds during a meeting of like-minded leaders 2,300 miles from the U.N. headquarters and 900 miles from the European mainland.

If the leaders can somehow break the impasse, a compromise would almost certainly provide a brief extension of the second resolution's March 17 deadline, officials said.

U.S. and foreign diplomats said another alternative was more likely: Blair would ask Bush and Aznar to withdraw the resolution rather than face certain defeat.

Almost immediately, the White House would shift to a war footing, said aides who are preparing a major war address by Bush.

The speech, which could come as early as Monday, is expected to serve as a final ultimatum for Saddam to disarm or face war, White House officials said.

Iraq remained defiant. In Baghdad, Abdel-Razzaq al-Saadi, the iman of Umm al-Maarek, or Mother of All Battles mosque, said in his sermon that it was "the obligation for Iraqis and others now to threaten U.S. interests everywhere and set them ablaze."