WASHINGTON — President Bush's "coalition of the willing," long seen by much of the world as a shell for a largely U.S. operation in Iraq, is quickly becoming a coalition of the unwilling.

Even as Bush sends more American forces to Baghdad, longtime war ally Tony Blair is pulling out British troops. Denmark is leaving. Lithuania says it may withdraw its tiny 53 troop contingent.

Bush's alliance is breaking up as opposition firms against the U.S. troop buildup — among the American and Iraqi people, in Congress and among Iraq's neighbors and some former U.S. allies.

"There is no military solution to the sectarian and insurgent conflict in Iraq," said Sen. Carl Levin, D-Mich., chairman of the Senate Armed Services Committee. He said the U.S. should follow the British prime minister's lead and start reducing forces.

The British announcement reverberated on the U.S. presidential campaign trail as well.

"I hope that since the president seems unwilling to listen to the results of the November election or to the new Democratic majority in Congress, that he would at least listen to someone who he has claimed has been his strongest ally in this effort," Democratic candidate Sen. Hillary Rodham Clinton said in an AP interview while campaigning in Nevada.

Blair has seen his popularity at home plummet since standing with Bush on the 2003 invasion. On Wednesday, Blair told Parliament that Britain would withdraw almost a quarter of its 7,100 troops in the coming months — and hoped to withdraw more by late summer.

That decision, along with drawdowns by other coalition members, goes against the course taken by the United States, which is sending 21,500 more troops into Iraq. There are currently 139,000 there, the Pentagon said Wednesday.

The Bush administration and Blair put a positive spin on the latest development, suggesting it represented success in stabilizing largely Shiite southern Iraq — not a retreat.

Analysts were skeptical, noting that most of the non-U.S. forces had been stationed in predominantly Shiite or Kurdish areas spared the intense sectarian violence that has rocked Baghdad-area neighborhoods.

"If the Brits really do have the ability to redeploy forces, we obviously need them in Baghdad and environs," said Michael O'Hanlon, a military analyst at the Brookings Institution and an adviser to the bipartisan Iraq Study Group. "The decision reflects British domestic politics, which prevent Blair from even considering sending some of those freed-up forces toward Baghdad."

Long gone from Bush's coalition are troops from Spain and Italy, whose leaders were booted out of office by voters unhappy with their war alliances with Bush.

Denmark recently said it would withdraw all its 460 troops by August. South Korea, which now has 2,300 in the northern Iraqi city of Irbil, plans to bring 1,100 home by April, and its parliament insists on a complete withdrawal by the end of 2007.

Secretary of State Condoleezza Rice said the British pullback squares with the U.S. plan to turn over more control to Iraqis. "The coalition remains intact and, in fact, the British still have thousands of troops deployed in Iraq," she said.

The Pentagon has stopped publicly listing the countries in the coalition and troop levels.

In a recent count by The Associated Press that includes information from individual coalition partners, 22 countries still have forces in Iraq. Only Britain and South Korea are contributing more than 1,000 each.

The next-largest contingents are Georgia and Poland, each with 900 combat forces; Romania, with about 600 troops, and Australia, with 550. Lithuania is seriously considering withdrawing its 53 from Iraq, Defense Ministry spokeswoman Ruta Apeitkyte, said Wednesday.

There are even smaller contributions: Estonia has 35 troops in Iraq; Kazakhstan, 27 military engineers; Netherlands, 15 soldiers as part of a NATO training mission, and Slovenia, four military instructors.

The British troop reduction "weakens the image of the coalition and further isolates the U.S.," said Anthony Cordesman, an Iraq expert at the Center for Strategic and International studies. "This is a war of perceptions."

Furthermore, Cordesman said, "I think that we have to understand that virtually every month that goes by, Iraqi tolerance for a U.S. presence declines."

The coalition may have outlived its usefulness, suggested John Pike, a defense analyst at GlobalSecurity.org, an Alexandria, Va., think tank. "Initially, the `coalition of the willing' served to legitimize the United States going in — in the absence of a U.N. mandate. Once we were in there, it served to legitimize the new and improved Iraq government."

Now, most coalition partners are helping to secure regions that can take care of themselves. "I wouldn't be surprised to see a lot of other coalition people pack their bags and go home too," Pike said.