President Barack Obama's stunning reversal on Syria — deciding to ask Congress to approve the use of force just hours after he seemed set on bypassing the legislative branch — amounts to a massive gamble by the commander in chief.

There is little certainty of the outcome of the vote, which will come the week of Sept. 9, when both houses of Congress return to Washington after the August recess. And, if Congress doesn't pass the resolution, Obama will be in an even smaller box, policy-wise, than he found himself at the end of last week following the British Parliament's rejection of a similar use-of-force resolution.

First, consider that roughly 40 percent of House Democrats voted against the use of force resolution against Iraq in 2002. (Unlike 2002, Democrats have one of their own in the White House now, but the 2010 election made the caucus more liberal — and more opposed to military action — than it was in 2002.)