So far the President seems to be winning the positioning battle: the coming vote will not directly be a vote of confidence in Obama; it will be a vote on America's willingness to act decisively and, when needed, militarily, in defense of its direct interests or essential international norms.
It will also test whether America can act cohesively in the world arena, when it cannot do so in its domestic affairs. This last point is central to Obama's case, and a key part, I believe, in explaining why he sought a vote at all. It's not just because of the "red line" that we are now told he mistakenly declared, although that is part of it. The big question some in the world have, and quite likely among that group are adversaries like Iran, is whether the US, split as it is politically, can nonetheless act powerfully on the world stage. A positive vote will demonstrate this to be true.
Had the anti-strike vote been successful in making this a vote on whether we want Obama to take the lead in a strike on Syria, he might have lost. Most likely, he would have won the Senate and lost the House, which would have meant a loss. This happened to Clinton in 1999 in the Kosovo bombing campaign: the Senate said yes; the House tied 213-213, thus not saying yes; and Clinton continued the bombing (already begun) until a successful conclusion six weeks later.
Boehner and Cantor have joined Senators McCain and Graham in support. Don't know that we've heard from McConnell yet. My prediction right now: solid win in the Senate; close call, but a win in the House. And because this will not be viewed as primarily an anti-Obama vote, the large number of House GOP voting No will be viewed as the new isolationist voice emerging in the Republican Party, connecting with libertarians Rand Paul and Mike Lee in the Senate.
Of course, as always, I could be wrong.