The Obama administration ran into roadblocks Thursday as it tried to corral an international coalition in support of intervention in Syria, with U.S. allies appearing to hit pause on calls for a missile strike.
Britain and France, which helped lead the 2011 mission to impose a no-fly zone in Libya, on Thursday were still in a wait-and-see mode on Syria, as the countries await the results of a United Nations investigation.
And unlike with Libya, the U.N. Security Council has so far not approved any action on Syria. The five permanent members reportedly will meet Thursday afternoon to discuss the situation.
Some of the fiercest deliberations unfolded in London, where British Prime Minister David Cameron faced down a skeptical Parliament as he tried to make the case for intervention.
Cameron argued that an attack on Syria in response to chemical weapons use would be legal. Met with skepticism in Parliament, though, Cameron said the motion he's put forward would require Britain to wait until U.N. weapons inspectors report their findings, until "further action" is taken at the U.N., and until another vote is held in Parliament.
In the end, Cameron lost a vote endorsing military action against Syria by 13 votes Thursday -- a stunning defeat for a government which had been poised to join the U.S. in strikes to punish Bashar Assad's regime for an alleged chemical weapons attack this month.
Cameron's nonbinding motion was defeated 285-272 and he conceded after the vote that "the British Parliament, reflecting the views of the British people, does not want to see British military action."
The prime minister said in terse comments that while he believes in a "tough response" to the use of chemical weapons, he would respect the will of the House of Commons.
The push for strikes against the Syrian regime began to lose momentum as Britain's Labour Party -- still smarting from its ill-fated decision to champion the invasion of Iraq in 2003 -- announced its opposition to the move.
Cameron gave concessions, promising to give the U.N. inspectors time to report back to the U.N. Security Council and to do his outmost to secure a resolution there. He also promised to give lawmakers a second vote in a bid to assuage fears that Britain was being rushed into an attack on Assad.
In the end, it wasn't enough to dispel lingering suspicions that what was billed as a limited campaign would turn into an Iraq-style quagmire.
The delay in London could prevent Obama from taking any action; however, his administration has signaled that it would be willing to move forward without international partners if necessary. U.N. Secretary-General Ban Ki-moon says inspectors are leaving the country on Saturday, meaning any report from them is not likely until next week at the earliest.
Meanwhile, Obama is facing his own set of problems in Washington, where lawmakers currently on summer recess are beginning to voice serious consternation about the possibility of a missile strike.
"It is essential that you provide a clear, unambiguous explanation of how military action -- which is a means, not a policy -- will secure U.S. objectives and how it fits into your overall policy," House Speaker John Boehner wrote in a letter to the president on Wednesday.
Secretary of State John Kerry and Secretary of Defense Chuck Hagel were briefing top lawmakers on Thursday, as the military continues to prepare for a possible strike. A fifth Navy Destroyer was sent into the eastern Mediterranean on Thursday.
One senior Hill aide said there was a concern that launching missiles at Syria could simply be a case of "fire and forget." Further, lawmakers are worried about the potential consequences of a bombing mission, and they want to know the endgame.
"We don't employ the U.S. military just to make a point," groused one congressional source who asked not to be identified.
In an interview with PBS on Wednesday, Obama bluntly declared that the Syrian government carried out a chemical weapons attack last week.
He suggested a "shot across the bow" for Syria could be in the interest of U.S. national security.
But while the administration is expected to release intelligence findings regarding last week's attack as early as Thursday, the Associated Press reported that officials say that intelligence is "not a slam dunk."
If there is even a shred of doubt that Assad and his top lieutenants ordered the strike last week, Obama is likely to face even more questions from Congress during briefings on Thursday. Many lawmakers are already demanding that he seek a formal vote before moving ahead with any strikes.
Meanwhile, battle lines are being drawing in the international community. After Russia refused to sign on to a Britain-drafted resolution before the U.N. Security Council on Wednesday, Reuters reports that Russia is sending two warships to the Mediterranean Sea, where the U.S. has also positioned ships. The Navy has also boosted its presence in the Persian Gulf, adding one more aircraft carrier.
Fox News' Chad Pergram and The Associated Press contributed to this report.