Syria's opposition expressed disappointment Sunday that President Barack Obama had put on hold military action against the Damascus regime, but said it was confident US lawmakers would green-light a strike.
To general surprise, the US leader on Saturday broke with decades of precedent to announce that he would seek approval from Congress for action against Syria's alleged use of chemical weapons.
This effectively pushed military action back until at least September 9, when US lawmakers return from their summer recess.
Obama insisted that he reserves the right to strike regardless of Congress's decision, and a White House official said the pause would also allow him time to build international support.
"We had a feeling of disappointment. We were expecting things to be quicker, that a strike would be imminent... But we believe Congress will approve a strike," said Samir Nashar, a top official at the Syrian National Coalition.
Nashar said the coalition was confident that Arab foreign ministers who meet Sunday in Cairo would give "very strong support" to US-led military action.
"The coalition will get in touch with Arab countries and Turkey so that they cooperate as much as possible with the United States," he said.
"We will try to push these countries to take part in the military operation, which will greatly alleviate the suffering of Syrians."
Obama travels to Russia next week for a G20 Summit that will now be overshadowed by the crisis.
Officials said Obama would lobby world powers on the sidelines of the St Petersburg summit, while at home the White House was reaching out to lawmakers.
But the toughest battle, and perhaps the most dangerous for Obama's credibility, may yet be with his own former colleagues in Congress, where support for strikes is far from assured.
Obama's Democrats control the Senate but the House of Representatives is in the hands of his Republican foes and both sides are divided on the issue, making the outcome uncertain.
Indeed, observers warned that Obama faces the same fate as Prime Minister David Cameron, who on Thursday lost his own vote on authorising military action in the British parliament.
"The chairman of the joint chiefs has informed me that we are prepared to strike whenever we choose," Obama warned during an address in the White House Rose Garden.
"Our capacity to execute this mission is not time-sensitive. It will be effective tomorrow or next week or one month from now."
At least five US warships armed with scores of Tomahawk cruise missiles have converged on the eastern Mediterranean ready to launch precision strikes on Syrian regime targets.
The FBI has meanwhile increased its surveillance of Syrians living in the United States ahead of a possible US attack and US authorities are also warning of possible retaliatory cyberattacks, The New York Times reported.
And France, which announced its "determination" alongside the US, said it is ready to deploy its own forces in the operation.
Syria, meanwhile, said it has its "finger on the trigger" as it braces for what it had formerly feared was an imminent Western strike.
"The Syrian army is fully ready, its finger on the trigger to face any challenge or scenario that they want to carry out," Prime Minister Wael al-Halqi said.
And the head of Iran's elite Revolutionary Guards warned that Western action would trigger reactions beyond the borders of Tehran's key regional ally.
"The fact that the Americans believe that military intervention will be limited to within Syrian borders is an illusion," said commander Mohammad Ali Jafari.
Shortly before Obama's remarks, a team of UN inspectors left Syria after spending four days investigating last week's alleged chemical attacks on suburbs of Damascus.
The Organisation for the Prohibition of Chemical Weapons said that analysis of samples taken at the site would take up to three weeks.
A UN spokesman promised they would give a fair report after conducting these lab tests, but Washington and its allies insist they already know all they need to know.
The Obama administration says it has reliable intelligence that the regime launched a chemical onslaught that killed 1,429 people, including at least 426 children.
President Vladimir Putin of Russia, a close ally of Syria, branded the claims "utter nonsense" and demanded proof.
Syria has denied responsibility for the alleged incident and has pointed the finger of blame at "terrorists" -- its term for the rebels ranged against Assad's forces.
In a bid to ease fears of another open-ended war, the White House formally asked Congress for authorisation to conduct military strikes in Syria in a draft resolution framing a narrow set of operations.
The document said support from Congress would "send a clear signal of American resolve."
More than 100,000 people have died since the Syrian conflict erupted in March 2011, and two million have become refugees, half of them children, according to the United Nations.