Lawmakers took the same line in responding to the sudden developments over the last 24 hours.
"While at this point I have healthy skepticism that this offer will change the situation and it will be several days before we can fully determine its credibility, I do know that it never would have been floated if the Senate Foreign Relations Committee had not approved the authorization for the use of force last week," Sen. Bob Corker, ranking Republican on the Senate Foreign Relations Committee, said in a statement.
Senate Foreign Relations Chairman Bob Menendez (D-NJ) said the same on CNN's "Crossfire" Monday night. Sen. Jeanne Shaheen (D-NH), who also voted for military strikes in committee, echoed the sentiment in a statement of her own.
"After two years of diplomatic stalemate, the credible threat of force has finally pushed Syria and Russia to the negotiating table," Shaheen said.
Even with the latest developments, a diplomatic solution is not a shoo-in, by any means. The Syrian opposition has said it opposes the Syria-Russia plan. Experts like the Brookings Institution's Michael Doran have called the proposal "a sham." As the administration acknowledges, there is still a long way to go before Syria's chemical weapons are secure -- and there's still a civil war raging.
While Obama, senior administration officials, and members of Congress have voiced skepticism about Syria's intentions and Russia's role as a deal broker, they acknowledged that it could be a way out of war. Votes in Congress have been postponed, and the president told interviewers Monday that if the Syria-Russia plan proved to be a success -- a big if -- the United States would "absolutely" put military strikes on hold.
"I consider this a modestly positive development," Obama told ABC News.
Things moved fast after Secretary of State John Kerry expressed openness Monday morning to a diplomatic alternative to resolving the crisis. The Russian government officially made the offer later Monday, and the Syrian government had accepted it by Tuesday morning.
The key to this positive momentum was the threat of military action, according to supporters of such strikes.
The White House official said that Obama and Russian President Vladimir Putin had discussed Syria surrendering its chemical weapons stockpile last June at the G-20 summit in Los Cabos, Mexico. The two talked over the possibility again last week in St. Petersburg. So the idea has been on the table for a while, even before the Aug. 21 attack in the Damascus suburbs and before Obama publicly supported military strikes in retaliation, but it was the threat of imminent strikes that brought it to fruition, as the White House tells it.
If this brinkmanship was the White House's plan all along, that was news on Capitol Hill. In conversations with TPM, Hill aides, Democrats and Republicans, saw the administration's openness to a diplomatic alternative not as part of a grand design, but as their last resort when the whip counts in Congress looked most grim.
"I think the White House thinks they found a life raft," a House Republican aide said Monday.