Washington (CNN) -- Former U.S. Secretary of State Hillary Clinton said Monday it would be an "important step" if Syria immediately surrendered its chemical weapons stockpiles to international control.
"But this cannot be another excuse for delay or obstruction. And Russia has to support the international community's efforts sincerely or be held to account," she said.
A potential Democratic contender for president in 2016 who left the State Department in January, Clinton received questions and some criticism for not speaking out immediately after chemical weapons were allegedly used by the regime of President Bashar al-Assad last month.
An aide said last week that she supported Obama's decision to seek congressional authorization to punish Syria militarily, but she had not publicly weighed in until her appearance at the White House on Monday.
Her comments came during an address on wildlife trafficking and followed a meeting with Obama.
She adhered to the White House line on Russia's proposal earlier in the day that Syria relinquish chemical weapons to international control to avert a possible U.S. military strike, which Obama is trying to get Congress to approve.
Syria welcomed the proposal, paving the way for a possible diplomatic solution to the crisis that comes amid a two-year civil war in Syria that has killed more than 100,000 people, according to U.N. estimates.
Clinton's successor, Secretary of State John Kerry, discussed a similar scenario, though the State Department stressed that al-Assad could not be trusted to give up his country's chemical stockpiles.
And just moments before Clinton's remarks, White House spokesman Jay Carney said the "credible threat" of a U.S. military attack on Syria led to the Russian proposal. But he said any such plan would require close evaluation and that Washington remained "highly skeptical" of the Syrian regime.
Clinton said Syria's alleged use of chemical weapons "violates a universal norm at the heart of our global order" and "demands a strong response" from the world led by the United States.
"This world will have to deal with this threat as swiftly and comprehensively as possible," she said.
Clinton did not say whether military action, as proposed by Obama, would be the best course. But she emphasized she will support the president and argued a "political solution that ends the conflict is in the interested of the United States."
She reiterated the White House's notion that Russia's proposal could have only taken place "in the context of a credible military threat by the United States to keep pressure on the Syrian government."
Behind the scenes, Clinton worked the phones for Obama, who is trying to convince Congress to go along with his plan for a limited, targeted military response.
Clinton, a former senator, called Arkansas Sen. Mark Pryor over the weekend, a source familiar with the call confirmed to CNN.
But Pryor had already made up his mind to vote against military action and announced his decision on Saturday.
The source would not speak on the record because the phone call was private.
A separate source familiar with the call confirmed Clinton also called Sen. Charles Schumer, D-New York, over the weekend.
He already supported military authorization when the call took place.
Clinton will likely repeat her White House comments during a speech Tuesday night at the National Constitution Center in Philadelphia, a Clinton source told CNN.
In addition to pushing for diplomatic efforts to remove al-Assad from power, Clinton backed a proposal last year to provide weapons to Syrian rebels when she served as secretary of state.
Clinton also issued warnings in January shortly before leaving office about Iran's involvement in Syria, saying the country was providing al-Assad's regime with military supplies. She urged Iran, as well as Russia, to reconsider their aid to the war-torn country.
As Obama's top diplomat during his first term, Clinton was automatically associated with the administration's response to the Syrian civil war until she stepped down early this year.
And she's faced some criticism for that response as debates over Syria heat up in Washington.
"Had President Obama and then-Secretary of State Hillary Clinton acted then in support of pro-democracy forces when that rebellion was taking place, we could have removed Assad and helped usher in stability for that country," former U.S. Sen. Rick Santorum said in a statement last week.
"But we have a very different situation today. After nearly two years, 100,000 people killed, a rebel force comprised of al Qaeda and a Syrian regime in a much stronger position, a military strike would no longer be in our national security interest," the former Pennsylvania lawmaker said.
Santorum is considered a potential candidate for the Republican presidential nomination in 2016.
Before leaving the State Department, Clinton defended her role in the situation.
"I've done what was possible to do," she told reporters.
Kevin Bohn, Catherine E. Shoichet, Jessica Yellin and Tom Cohen contributed to this report.