WASHINGTON (AFP) - War weary US lawmakers earned a stunning victory on Saturday as President Barack Obama bowed to their demand that he seek congressional approval for any military action against Syria.
The question now is, will members of the US House and Senate endorse his push for action, or hand the president a bitter defeat despite his declaration that the Syrian regime used chemical weapons against its own people?
Mr Obama's rare announcement - many presidents including Mr Obama have launched military action without congressional approval in recent decades - sets up one of the most hotly-anticipated debates of the year when Congress returns from its summer recess on Sept 9.
Mr Obama may feel confident of winning any vote put before the Democrat-controlled Senate, which also includes a number of Republicans who have voiced support for military action.
However his chances of winning support from the House of Representatives, where the Republicans hold the balance of power, are less certain. The chamber is home to a hard core of conservatives who have obstructed Mr Obama's agenda at every turn.
The jockeying began earlier this week, when some 170 lawmakers from both parties signed letters calling on Mr Obama to seek a congressional green light before taking action in the war-ravaged Middle Eastern state, where President Bashar al-Assad is clinging to power after more than two years of bloody civil war.
Now that Mr Obama is turning to Capitol Hill, the lawmakers themselves will be in the spotlight, and Republican Senator Bob Corker - who supports a limited "surgical" strike against Syria - hinted at the tough time the president will have in drumming up sufficient support.
Mr Corker told CNN that Mr Obama should use "every ounce of political capital that he has to sell this."
"I think it is problematic and it could be problematic in both bodies," he said of the authorisation vote.
"Today, I do not think the country is there, and it is very important for the president to lay out why he wishes to do this and, candidly to us privately, how he wishes to do this." Republican House Armed Services Committee chairman Buck McKeon spoke for many when he said he is appalled by Assad's actions, but nevertheless wants a full debate on whether and how to intervene.
"Authorisation for the use of force in this case should be contingent on the president setting clear military objectives that can meet articulated policy goals, including degrading any party's ability to use these weapons again," McKeon said.
House Speaker John Boehner has discussed the Syria options with Mr Obama but stressed that the president now has to "make his case to Congress and the American people."
He and the rest of House Republican leadership released a statement approving of Mr Obama's decision "in response to serious, substantive questions being raised."
Few lawmakers have come out in full-throated opposition to a military strike, but Senator Chris Murphy has, stressing this week that bombing Syria would do little to reduce the threat to US national security, and may well open the door for another decade-long US war.
Number two Senate Democrat Dick Durbin sounded a note of caution as well on Saturday, recalling how the "cost of lives and treasure to our country over the last 12 years of war has been overwhelming.
"If we can do something to discourage Assad and others like him from using chemical weapons without engaging in a war and without making a long-term military commitment of the United States, I'm open to that debate." Congress has its clear supporters for military action on both sides of the aisle.
"As far as I'm concerned, we should strike in Syria today," Democratic Senator Bill Nelson said in a terse statement.
"The use of chemical weapons was inhumane, and those responsible should be forced to suffer the consequences." But two usually reliable backers of military interventions, Republican Senators John McCain and Lindsey Graham, threw a spanner in the works.
"We can not in good conscience support isolated military strikes in Syria that are not part of an overall strategy that can change the momentum on the battlefield, achieve the president's stated goal of Assad's removal from power, and bring an end to this conflict," they said.
"Anything short of this would be an inadequate response to the crimes against humanity that Assad and his forces are committing." One congressman, Republican Peter King, went so far as to say Mr Obama was "abdicating his responsibility as commander-in-chief" by turning to Congress for permission to attack.
"The president doesn't need 535 members of Congress to enforce his own red line," Mr King said.