An emergency closed-door meeting of the UN Security Council on Syria was canceled after Russia withdrew its request for the session, Australia's UN envoy said on Tuesday.

"Following withdrawal of the request for consultations, Security Council meeting scheduled for 4 p.m. (2000 GMT) will not proceed," Australian Ambassador Gary Quinlan, president of the 15-nation council this month, announced on his Twitter feed @AustraliaUN.

The meeting was expected to focus on a Russian plan to place Syrian chemical weapons under international control, diplomats said on condition of anonymity.

Russia told France earlier on Tuesday that the proposal to adopt a UNSC resolution was unacceptable. Russian Foreign Minister Sergei Lavrov told his French counterpart that Moscow would propose a UN draft declaration supporting its initiative, the Foreign Ministry said in a statement.

Britain, France and the United States will table a resolution on Syrian chemical weapons in the United Nations Security Council later on Tuesday, said British Prime Minister David Cameron, reacting to a Russian proposal for Syria to surrender such arms.

Cameron, who said he had just spoken to U.S. President Barack Obama about the issue, told lawmakers: "If this is a serious proposal then we should act accordingly and I think a UN Security Council resolution is a good idea."

Earlier Tuesday, a White House official said that the Obama administration will begin discussions with the UN Security Council onthe Russian Proposal, a White House official said.

Obama also spoke on the phone earlier with French President Francois Holland and British Prime Minister David Cameron about the Russian proposal.

"They agreed to work closely together, and in consultation with Russia and China, to explore seriously the viability of the Russian proposal to put all Syrian chemical weapons and related materials fully under international control in order to ensure their verifiable and enforceable destruction," the White House offical said.

"These efforts will begin today at the United Nations, and will include a discussion on elements of a potential UN Security Council Resolution," the official said in a statement.

Defense Secretary Chuck Hagel told a congressional hearing on Tuesday that the U.S. is hopeful the Russian proposal might avert the need for military strikes, but Washington must uphold that threat for any diplomatic option to succeed.

"All of us are hopeful that this option might be a real solution to this crisis. Yet, we must be very clear-eyed and ensure that it's not a stalling tactic," Hagel said. "For this diplomatic option to have a chance of succeeding, the threat of a U.S. military action - the credible, real threat of U.S. military action - must continue."

In an address Tuesday evening, Obama will tell the American people and Congress on that the U.S. must not let up pressure on Syria even as Washington explores a diplomatic alternative to military strikes.

While Obama plans to claim credit for a potential diplomatic breakthrough on Syria's chemical weapons, he still faces potential political damage from his failure so far to sell the public and Congress on the need for military intervention.

Diplomacy took center stage on Capitol Hill as supporters and opponents of a military strike in Syria urged a pause in the process so the administration can explore Russia's proposal to put Syria's chemical weapons arsenal under international control.

The U.S. Senate put the brakes on a planned vote on authorization of military force in Syria as lawmakers assess the new diplomatic push and the public response to Obama's speech on Tuesday night.

"The Senate should give these international discussions time to play out, but not too much time," Senate Democratic leader Harry Reid said on Tuesday.

Obama will visit Senate Democrats and Republicans in separate meetings at the Capitol on Tuesday before making his nationally televised address from the White House. Spokesman Jay Carney said the president will keep pushing Congress to approve military force.

Syria's recent acceptance of a Russian proposal to give up its chemical weapons came about because of the U.S. threat of military strikes, Carney told MSNBC.

"We see this as potentially a positive development and we see this as a clear result of the pressure that has been put on Syria," Carney said when asked for the White House reaction to new reports that Syria will cede control of its stockpile.

Obama has said Syrian President Bashar Assad needs to be held accountable for an August 21 poison gas attack that killed more than a thousand civilians, including hundreds of children, and asked Congress to authorize limited military strikes.

But the plan has been deeply unpopular with Americans, polls show, and faces stiff resistance in a Congress where many lawmakers had not made up their minds.

Senate Republican leader Mitch McConnell said he would oppose a resolution on military force in Syria because "a vital national security risk is clearly not in play."

'Strict timeline needed'

House of Representatives Speaker John Boehner, a Republican who announced last week he would support a strike, said the American people still did not support military action in Syria and Obama needed to make a stronger case.

Influential Republican Senator John McCain, a strong supporter of military action in Syria, said he was working to modify the congressional resolution authorizing U.S. military force to include a "strict" timeline for Damascus to turn over chemical weapons.

McCain said he was "extremely skeptical" about such a diplomatic solution but it would be a mistake not to pursue it.

"Some of us are already working on a modification to a congressional resolution that would require strict timelines and strict guidelines that would have to be met as part of the authorization for the president," he said on CBS' "This Morning" program.

McCain offered few specifics about his measure, but other lawmakers have also been floating proposals that would allow a certain window of time before allowing Obama to take further action, which could include air strikes.

U.S. Secretary of State John Kerry told the House Armed Services Committee it was "the credible threat of military force" that prompted Assad to even acknowledge his chemical weapons stockpile.

In a televised address to the nation at 9 P.M. ET (1 A,M. GMT Wednesday), Obama will explain to Americans why he wants to have permission to strike Syria, Carney said.

"He will also, as he did last night in response to questions from network anchors, note that we have some potential progress on the diplomatic front because of the credible threat of U.S. military force," he said.