By Roberta Rampton and Thomas Ferraro
WASHINGTON (Reuters) - President Barack Obama, struggling to gain support for U.S. military action in Syria, called Russia's proposal on Monday to put Syria's chemical weapons under international control a "potentially positive" move that should be viewed skeptically.
Democratic Senate leader Harry Reid pushed back a Senate test vote on whether to authorize military strikes against Syria that had been scheduled for Wednesday as lawmakers evaluate the Russian plan. The vote is still expected this week.
In a round of six television interviews on Monday, Obama said he prefers a diplomatic solution in Syria and will have U.S. Secretary of State John Kerry explore the Russian proposal.
"I think you have to take it with a grain of salt initially," Obama told NBC News on the Russian offer. "But between the statements that we saw from the Russians, the statement today from the Syrians, this represents a potentially positive development. We are going to run this to the ground."
However, administration officials also said the proposal would not derail efforts to get congressional authorization for strikes, saying the threat of strikes motivated Russia's offer.
Obama faces an uphill struggle to win approval on military intervention from Congress, where a majority of lawmakers are still undecided on whether to use military force to punish Syria for an August 21 chemical weapons attack on civilians.
"I wouldn't say I'm confident" of winning approval, Obama told NBC, but he plans an intensified lobbying blitz for support over the next few days.
In addition to the six interviews, Obama was due to visit the Capitol on Tuesday to make his case to lawmakers from both parties before making a televised address to the nation from the White House in the evening.
The Russian offer provided the administration a new option on Syria. It came a few hours after Kerry had suggested in London, in response to a reporter's question, that Syrian President Bashar al-Assad could avoid a military strike by surrendering his chemical arsenal.
Syria's Foreign Minister Walid al-Moualem "welcomed" the Russian proposal.
Britain and France gave tentative support, and U.N. Secretary-General Ban Ki-moon separately said on Monday he may ask the U.N. Security Council to demand that Damascus move its chemical arms stocks to sites where they can be safely stored and destroyed.
A senior U.S. official described Kerry's comment as rhetorical, but said Kerry told Russian Foreign Minister Sergei Lavrov in a later phone call that while he was skeptical about the prospect he would examine any serious proposal.
Administration officials emphasized, however, that the Russian effort should not be an excuse to delay congressional authorization of a military strike.
"It's important to note that this proposal comes in the context of the threat of U.S. action and the pressure that the president is exerting," Obama's deputy national security adviser, Tony Blinken, told reporters at the White House.
Some lawmakers reacted positively to the Russian plan. Republicans John McCain and Lindsey Graham, leading supporters of the strikes, said the Russian proposal should make it easier to win support in Congress.
Senator Dianne Feinstein, Democratic chairwoman of the Senate Intelligence Committee, said Russia could be "most effective" in encouraging Assad to place his chemical arsenal under U.N. control.
Former Secretary of State Hillary Clinton, a potential presidential candidate in 2016, waded into the debate, endorsing Obama's drive for Congress to approve military action.
She said the surrender of chemical weapons would be an "important step" but said such a proposal could only have come "in the context of a credible military threat by the United States."
(Additional reporting by Arshad Mohammed, Susan Heavey, Caren Bohan, Richard Cowan, Patricia Zengerle and Deborah Charles; Editing by Karey Van Hall, David Storey and Jim Loney)