WASHINGTON -- The United States will begin working with its allies at the United Nations to explore the viability of a Russian plan to avert military action against Syria by having the international community take control of the Syrian chemical weapons stockpile, a senior White House official said on Tuesday.
The decision to work through the United Nations came after President Obama spoke Tuesday morning with President François Hollande of France and Prime Minister David Cameron of Britain, the White House official said.
"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 official said. "These efforts will begin today at the United Nations."
A meeting of the Security Council had been scheduled for Tuesday afternoon but was canceled at Russia's request, according to United Nations diplomats.
The rapid-fire diplomatic developments elicited some skepticism from many regional and international players, who questioned the motives behind the Russian gambit and speculated that Moscow's plan would enable the Syrian authorities to buy time. There are also questions about the viability of the plan, which is still being developed.
France has already begun to share a draft Security Council resolution on Syria, which members of the council were consulting about on Tuesday afternoon. "Discussions have just begun," said a United Nations diplomat, speaking on the condition of anonymity. "We're looking at a process that will last a few days."
But Russia's Foreign Ministry announced in a statement that it opposed any resolution that would authorize the use of force. Sergey V. Lavrov, the Russian foreign minister, telephoned his French counterpart and told him a resolution like the one proposed by France was "unacceptable," the ministry said in a statement.
Instead, Russia will propose a presidential statement, which is far less binding, calling on the secretary general and the organization that oversees the Chemical Weapons Convention to carry out the proposal to put Syria's arsenal under international control.
"The Russian draft confirms that there is no alternative to a political and diplomatic settlement of the conflict" in Syria, the statement said.
Mr. Obama's decision to embrace a United Nations process came as he prepared to consult with senators on Capitol Hill and deliver a speech to the nation Tuesday night, which was originally scheduled to explain why he was asking Congress for authorization to take military action against the government of President Bashar al-Assad in retaliation for its use of chemical weapons.
Aides to Mr. Obama said he would continue to press for military action against Syria, but the proposal floated Monday by Mr. Lavrov has transformed both the domestic and international debate over Mr. Obama's plan after he appeared to be waging a losing battle to win support for a military response.
Under the Russian proposal, international monitors would be sent to Syria to take control of the chemical stocks, which would ultimately be eliminated. Syria has welcomed the Russian initiative but has not specifically endorsed the idea of disposing of its huge chemical weapons arsenal.
In Moscow, Russian officials said they were working with the authorities in Damascus on a "workable, precise and concrete plan" to advance the proposal, which received public endorsements from Syria's foreign minister and prime minister, but not from Mr. Assad himself.
President Vladimir V. Putin of Russia said that the proposal to take control of Syria's chemical weapons -- and to resolve the crisis in general -- was possible only if the United States and others forswore the use of military force. He said he had discussed the issue with Mr. Obama on the sidelines of the Group of 20 meetings in St. Petersburg last Friday. Mr. Putin also said he welcomed the initial response of Syrian officials.
"Undoubtedly, all of this makes sense and can function, can work, only if we hear that the American side and those who support the United States in this sense rule out the use of force," Mr. Putin said in televised remarks on Tuesday night, "because it is difficult to make any country -- Syria or any other country, any other government in the world -- unilaterally disarm if the use of force is being prepared against it."
He noted that Syria had "a certain arsenal of chemical weapons," and that "the Syrians have always regarded it as an alternative to the nuclear weapons in Israel." He said he and Mr. Obama had agreed to ask Mr. Lavrov and Secretary of State John Kerry to work intensively to try to resolve the issue.
Syria's foreign minister appeared to acknowledge for the first time on Tuesday that the Syrian government possesses chemical arms, and he declared that the country aimed to become a signatory to the international convention banning the weapons.
The indirect admission came as the foreign minister, Walid al-Moallem, suggested that Mr. Assad's government was ready to accept a deal to get rid of the weapons in order to avoid an American military strike.
"We are ready to reveal the locations of the chemical weapon sites and to stop producing chemical weapons and make these sites available for inspection by representatives of Russia, other countries and the United Nations," Mr. Moallem said in a statement, which he read on Al Mayadeen, a Lebanese television station that leans in favor of the Syrian government.
Mr. Moallem also said Syria was "ready to cooperate fully" with the initiative, "particularly given that we want to become a signatory to the Chemical Weapons Convention." A similar statement was also released to a semiofficial news agency in Russia.
On Capitol Hill on Tuesday, a bipartisan group of eight senators announced plans for a new Congressional resolution that would authorize an attack on Syria, but only after the introduction of a United Nations resolution that would set a deadline for the Assad government to hand over its chemical weapons stockpile. If that deadline is not met, the resolution would authorize the use of military force.
If the resolution gains support, it could stave off a debilitating defeat for the Obama administration on a resolution authorizing an attack that was approved by the Senate Foreign Relations Committee last week, but that had been losing ground in both parties in recent days.
Senators emerged from extended meetings with Mr. Obama optimistic that Congress could shift a resolution authorizing force to one that would give diplomacy more time.
The president impressed on them the need to keep the pressure on Syria and Russia with a credible threat of military force, but he expressed support for a delay in any vote until the United Nations Security Council makes clear what it plans to do. Senators said he was open to the developing new approach.
Mr. Kerry, appearing before a Congressional committee Tuesday morning, expressed caution about the diplomatic efforts even as he pledged that the president would "take a hard look at" the Russian plan in the days ahead. Mr. Kerry said any diplomatic response to the chemical weapons attack in Syria must be viewed cautiously.
"It has to be swift, it has to be real, it has to be verifiable," Mr. Kerry told members of the House Armed Services Committee. "It cannot be a delaying tactic."
Mr. Kerry said the administration would continue to push for Congress to authorize military action against Syria, believing that the threat of an attack had prompted the new diplomatic initiative. "The use of force absolutely should not be off the table," Mr. Kerry said.
Defense Secretary Chuck Hagel, appearing at the same committee hearing, said in his prepared statement that "for this diplomatic option to have a chance of succeeding, the threat of U.S. military action must continue to be very real and credible."
"So Congress has a responsibility," he added, "to continue this important debate on authorizing the use of force against the Syrian regime."
While Mr. Obama said on Monday that the Russian proposal might produce a diplomatic breakthrough, there is concern among American officials that it may be a maneuver to undermine the administration's effort to mobilize international and Congressional support for a military strike.
Obama administration officials have previously discussed the idea of some sort of ultimatum that might be presented to Mr. Assad to give up his chemical weapons stocks, a senior administration official said on Monday. But the idea seemed to have many problems. Among the questions was: How would the stocks be secured and transported out of Syria during a war? And how would inspectors ensure that stocks were not hidden?
The administration had dismissed the United Nations for days, saying that diplomacy there had failed to rein in Mr. Assad. Susan E. Rice, the national security adviser, said Monday morning that Mr. Obama believed that the United Nations Security Council had been ineffective.
By Tuesday morning -- with governments around the world seizing on the Russian proposal as a serious idea -- the White House tone had changed. The White House official said that the efforts at the United Nations would "include a discussion on elements of a potential U.N. Security Council resolution."
Developments in Congress reflected the fast-moving diplomacy.
In the Senate, which had already delayed an initial vote on military strikes that had been scheduled for Wednesday, the bipartisan group drafting an alternative Congressional resolution said its plan would give the United Nations time to take control of the Syrian government's arsenal of the internationally banned weapons.
The alternative resolution is far from complete, but a Senate aide familiar with the talks over its wording said the negotiations were being conducted in consultation with the White House.
The shifting direction in the Senate began taking shape well before Russia advanced a new diplomatic path forward when it became clear that a straightforward resolution authorizing force was highly unlikely to pass the Senate. Senator John McCain, Republican of Arizona and one of the strongest supporters of a strike, contacted a fellow Republican hawk, Senator Lindsey Graham of South Carolina, on Saturday to try to put together a new negotiating group.
Negotiations on a new resolution began in earnest on Monday. Mr. McCain and Mr. Graham met in the Capitol and brought in two senior Democrats, Senator Carl Levin of Michigan, who is the chairman of the Senate Armed Services Committee, and Charles E. Schumer of New York, the Senate's third-ranking Democrat. On Monday evening, after a vote in the Senate, two more Republicans, Kelly Ayotte of New Hampshire and Saxby Chambliss of Georgia, and two other Democrats, Chris Coons of Delaware and Bob Casey of Pennsylvania, joined the negotiations. Senator Robert Menendez of New Jersey, the chairman of the Foreign Relations Committee, was also involved in the discussions. The next session was to be held Tuesday afternoon or evening.
The approach quickly gained supporters in both parties, but senators joining the talks said Syrian compliance would have to come quickly.
Mr. Graham cautioned that no one should conclude that the new negotiations would produce a resolution strong enough to maintain a credible threat but capable of passing Congress.
"I don't know if this is going to go anywhere," he said. "I'm not going to embrace a U.N. path until I see it's real."
Reporting was contributed by Alan Cowell from London, Steven Lee Myers from Moscow, and Rick Gladstone from New York.
This article originally appeared in The New York Times.