The French nuclear-powered aircraft carrier Charles de Gaulle is seen in the Mediterranean port in Toulon.The French parliament will hold an extraordinary session on Sept. 4 to discuss the situation in Syria. (STRINGER/FRANCE/REUTERS)

French President François Hollande came under heightened pressure Monday to secure the backing of lawmakers before taking military action in Syria, with his position significantly complicated by President Obama’s decision to consult Congress ahead of any strike.

Hollande, a vocal critic of Syrian President Bashar al-Assad, has long stood with British Prime Minister David Cameron in calling for tougher action. But after Cameron’s parliamentary defeat last week over military action in Syria and Obama’s weekend move, Hollande finds himself facing a new set of political risks.

France’s National Assembly is set to debate possible Syria action on Wednesday, but lawmakers are not scheduled to vote on a resolution. Under French law, Hollande does not need to call a vote until four months after any intervention has started, and he has, thus far, rejected one prior to any strike.

But Hollande’s opponents say a decision not to allow a vote would leave Paris out of step with other world capitals.

“I think there should be a vote of Parliament,” Arnaud Danjean, a center-right French member of the European Parliament, told the France 24 television channel. “We see the skepticism of the people, and we see the skepticism of our allies.”

Timeline: Unrest in Syria

Two years after the first anti-government protests, conflict in Syria rages on. See the major events in the country's tumultuous uprising.

The government in Paris is nevertheless pressing for action, with Prime Minister Jean-Marc Ayrault meeting with top French lawmakers to disclose domestic intelligence on an alleged Aug. 21 chemical attack by the Assad regime.

The evidence, according to a nine-page summary posted on the French government’s Web site, described the “massive use of chemical agents” thought to be deployable only by Assad or the “most influential members of his clan.”

A French review of video footage counted at least 281 dead, but French experts also concluded that other estimates as high as 1,500 were consistent with the likely number of fatalities from such an attack.

Hollande’s opponents argue that Cameron, too, had the power to act without parliamentary approval but decided to consult with lawmakers because of the complexity of the Syrian conflict.

French analysts say Hollande faces a difficult choice. A decision to act without the backing of lawmakers would raise questions about his mandate, but a parliamentary vote would carry the risk of the same kind of surprise political setback suffered by Cameron last week. In addition, Hollande would probably have to wait until Congress decides, lest he leave Paris in the embarrassing position of having to back away from military action if Capitol Hill rejects it.

“This act cannot be left without a response,” Ayrault told reporters in Paris late Monday, referring to the alleged chemical attack. But, he added, “it is not for France to act alone. The president is continuing his work of persuasion to bring together a coalition without delay.”

In an interview with the newspaper Le Figaro published Monday, Assad warned that France would face “repercussions” if it joined in an attack, which he said risked igniting a “regional war.”

“Everyone will lose control of the situation once the powder keg explodes,” he told the paper. “Chaos and extremism will spread.”

In Britain, Cameron faced calls from some quarters of his Conservative Party to return to Parliament and try again to win authority for a Syria strike. But the government seemed to dismiss the possibility, with a spokesman saying there were “no plans” to attempt a second vote.

British Defense Secretary Philip Hammond, however, seemed to leave the door slightly open, telling Parliament on Monday that a second vote could take place if “circumstances change very significantly.” He did not elaborate.

In the wake of Britain’s decision to opt out of any strike, analysts said French participation in any U.S.-led military intervention in Syria would be crucial to the Obama administration’s hopes of establishing international credibility for action. On Monday, NATO Secretary General Anders Fogh Rasmussen said he was convinced that the Syrian regime was behind the Aug. 21 attack and called for strong action. But he made clear that he did not foresee a broader NATO role and said it would be up to individual member nations to decide how to respond.

At the same time, Russian Foreign Minister Sergei Lavrov stepped up the pressure on Washington. Responding to U.S. claims that it had presented Russia with irrefutable evidence of the Assad regime’s culpability, Lavrov said, “There are no facts there.”

“When we ask for more detailed proof, they say, ‘You know, it’s all secret, so we cannot show it,’ ” he said, according to the Reuters news agency. “That means there are no such facts.”

If Hollande does join a U.S.-led coalition, it would raise the prospect that the very nation savaged in Washington for rejecting the 2003 Iraq invasion could emerge as the leading European partner in any Syria strike.

Yet even if the French participate and the British — traditionally the staunchest U.S. ally in Europe — sit this one out, few analysts see a long-term shift in which Paris replaces London as the go-to ally for Washington.

Rather, France has a number of rationales for acting in Syria that might not carry into the future. For one, France is the former colonial power there and sees Damascus as being within its sphere of influence. For years, Paris has smarted at Assad’s involvement in another former French colony, Lebanon.

“This is payback time for France,” said Fawaz Gerges, a professor of international relations at the London School of Economics and Political Science. “The Assad regime has given them a hard time.”

In addition, by sitting out the war in Iraq, French politicians lack the same baggage as those in Britain, whose troops joined the U.S.-led mission in Iraq based on false intelligence about weapons of mass destruction. That has made any decision to participate in Syria action easier for the Elysee Paris than it is for No. 10 Downing Street.

Without question, France has recently been flexing its military might, helping lead the allied operation in Libya two years ago and taking unilateral action this year in Mali. Yet, France has long judged its foreign-policy objectives to be somewhat separate and distinct from purely “Anglo American” goals. That makes it unlikely that Paris would easily fill any void left by Britain should its decision last week signal a future unwillingness to cooperate in coalition military operations.

“No matter what happens in Syria, France is not going to become the dominant ally of the United States,” said Dominique Moïsi, senior adviser at the French Institute of International Relations in Paris. “It’s not going to happen.”

Karla Adam contributed to this report.