Presidents usually prevail on issues like this, where they can argue that national security is at stake, and the administration can probably round up enough votes in the democratic-majority Senate.
That will be much harder in the Republican-majority House. Speaker John Boehner and Minority Leader Nancy Pelosi have both endorsed a resolution.
But Boehner and Democrat Chris Van Hollen have both called this a conscience vote and said their parties will not whip the issue. The White House will have to do the hard work of rounding up the votes.
At midweek The Washington Post listed only 17 House members favoring military action and 130 opposed or leaning against.
Most House Democrats voted against the Iraq War resolution in October 2002, when most voters favored it. Their party has dovish instincts going back to the Vietnam War and has been largely ignored by the administration since it lost its House majority in 2010.
House Republicans, the object of Obama's continued denunciations and disdain, are not inclined to trust him at all. Many surely believe they're being set up as fall guys for a president whose chief political goal is regaining the House majority for Democrats in 2014.
That suspicion was surely enhanced in Sweden on Wednesday when Obama said, "I didn't set a red line. The world set a red line."
But the world is not clamoring to enforce it. The only nation contemplating joining the United States in military action is France. That's 38 fewer allies than joined the United States after the supposed unilateralist George W. Bush, with congressional authorization, ordered troops into Iraq.
Former Bush administration official Elliott Abrams has argued that Obama's foreign policy is designed to restrain and reduce America's power in the world. The twists and turns of his policy toward Syria certainly seem to be having that effect.