Recent presidents have all claimed the authority to undertake limited military action without congressional backing. Some have followed up with such action.
Obama said he, too, believes he has that authority, and House Democratic leader Nancy Pelosi said during the day that even Congress' refusal to authorize the president wouldn't negate the power of the commander in chief.
Still, the president also has stated that the United States will be stronger if lawmakers grant their support. But neither Obama nor his aides has been willing to state what options would be left to him should Congress reject his call.
As Obama has often noted, the country is weary of war after more than a decade of combat deaths in Afghanistan and Iraq, and there is residual skepticism a decade after Bush administration claims went unproven that Saddam Hussein possessed weapons of mass destruction. Additionally, a spate of polls indicates the public opposes a military strike against Syria, by a margin of 59-36 percent if the United States acts unilaterally, according to a new Washington Post-ABC survey, and a narrower 46-51 if allies take part.
Among major allies, only France has publicly offered to join the United States in a strike, although President Francois Hollande says he will await Congress' decision. The British House of Commons rejected a military strike last week.
Yet the president's decision to seek congressional approval presents lawmakers with a challenge, as well.
Even some of Obama's sternest critics in Congress expressed strong concerns about the repercussions of a failure to act.
House Majority Leader, Eric Cantor, R-Va., said after Tuesday's White House meeting that a failure to respond to the use of chemical weapons "only increases the likelihood of future WMD (weapons of mass destruction) use by the regime, transfer to Hezbollah, or acquisition by al-Qaida."
America's largest pro-Israel organization, AIPAC, also announced its support for legislation to authorize a military strike.
Apart from the meeting with Obama, the White House provided closed-door briefings for members of Congress.
Sen. Jeff Flake, R-Ariz., said after attending one session that administration officials told lawmakers that the targets the military had identified last week were still present, despite the highly public discussion of a possible attack. "Seems strange to see some targets still available several weeks later," Flake said, adding that he was "still listening" to the administration's lobbying.
Dempsey addressed the same point later in the day. "Time works both ways," he told the Senate panel. He said the United States has significant intelligence about Assad's actions, and "we continue to refine our targets."
Others were firmly opposed. Sen. Jim Inhofe of Oklahoma said on Fox News, "It may sound real easy when people like Secretary Kerry say that 'it is going to be quick and we're going to go in, we're going to send a few cruise missiles, wash our hands and go home.' It doesn't work that way. This could be a war in the Middle East, it's serious."
Paul, the Kentucky Republican who has close ties to tea party groups, said he probably would vote against authorizing Obama to use force. But he said it also wouldn't be helpful to amend the resolution in a way that constrains the president too much to execute military action, if authorized.
He made his prediction that the White House would get its way in an exchange with Kerry in which he said Obama should agree to abide by Congress' decision, rather than reserve the right to order a strike even if the vote goes against him.
Democrats, too, were divided, although it appeared the administration's biggest concern was winning support among deeply conservative Republicans who have battled with the president on issue after issue since winning control of the House three years ago.
The United States maintains a significant military force in the eastern Mediterranean Sea. The U.S. Navy released one of the warships that had been in the region, leaving four destroyers armed with cruise missiles, the USS Stout, USS Gravely, USS Ramage and USS Barry. Also in the area was an amphibious warship, the USS San Antonio, with about 300 Marines aboard.
In addition, there are two aircraft carriers in the region - the USS Nimitz strike group, which is in the southern Red Sea, and the USS Harry S Truman, which is in the Arabian Sea.