President Obama says he will appeal directly to the American people on the need for limited U.S. military action in Syria during a televised national address on Tuesday evening from the White House.
A deeply skeptical public remains Obama's biggest hurdle to winning authorization from Congress to use military force against President Bashar al-Assad after he allegedly used chemical weapons in the Syrian civil war.
Speaking at a solo press conference at the conclusion of the G20 summit in St. Petersburg, Russia, Obama made a forceful case for the United States as an activist power responsible for enforcing global norms when international bodies fail.
"When there's a breach this brazen of a norm this important, and the international community is paralyzed and frozen and doesn't act, then that norm begins to unravel," Obama said of the longstanding international prohibition against the use of chemical weapons.
"If that norm unravels, then other norms and prohibitions start unraveling, and that makes for a more dangerous world, and that then requires even more difficult choices and more difficult responses in the future," he said.
Obama claimed that there was a "unanimous," if private, conclusion among world leaders attending the summit that chemical weapons were used in a Syrian attack on Aug. 21 and that it required an international response. But he said deep division remained over whether any use of force should hinge on United Nations approval.
Russia, which has veto power on the U.N. Security Council, stands staunchly opposed to military intervention in Syria and has blocked all previous attempts at condemnation of Assad's tactics.
"I was elected to end wars and not start them," Obama said. "But what I also know is that there are times where we have to make hard choices if we're going to stand up for the things that we care about. And I believe that this is one of those times."
The president acknowledged his argument is a "heavy lift" for the American people and conceded that "it's conceivable that, at the end of the day, I don't persuade a majority of the American people that it's the right thing to do."
But, he said, members of Congress need to consider the lessons of World War II and consider their consciences, even if it means going against the opinion of majorities of their constituents.
"Each member of Congress is going to have to decide if I think it's the right thing to do for America's national security and the world's national security," Obama said. "Ultimately, you listen to your constituents, but you've got to make some decisions about what you believe is right for America."
The president said he remains hopeful that public opinion will begin to turn in the coming days, but it remains an uphill climb. The latest ABC News/Washington Post poll finds nearly six in ten Americans oppose military intervention in Syria. White House officials have been making a full-court press to members of Congress and key outside constituencies trying to win their support.
"I do think that it would be easier if there was a stronger case being made to the American people," House Minority Leader Nancy Pelosi told the L.A. Times today. "People have to really know more about why the president has made this decision."
The White House has asserted the authority to act against Syria even without permission from Congress, and Obama today did not rule out proceeding on his own, disputing comments from deputy national security adviser Tony Blinken, who said earlier Friday that it's "neither his [Obama's] desire nor his intention to use that authority absent Congress backing him."
"I don't think that's exactly what he said," Obama said in response to a question from ABC's Jonathan Karl. Blinken made the comments to NPR.