But not McConnell. In a speech you can watch in its entirety below, the Senate Republican leader explained his opposition on the Senate floor.
Here's the line that sums up his position: "I will be voting against this resolution. A vital national security risk is clearly not at play, there are just too many unanswered questions about our long-term strategy in Syria, including the fact that this proposal is utterly detached from a wider strategy to end the civil war there, and on the specific question of deterring the use of chemical weapons, the president’s proposal appears to be based on a contradiction. Either we will strike targets that threaten the stability of the regime — something the president says he does not intend to do — or we will execute a strike so narrow as to be a mere demonstration."
In making his case, McConnell tied together the president's broader record on foreign policy and the specifics of the situation in Syria as the basis of his reasoning.
Left unmentioned: politics. There is no reason to doubt the sincerity of McConnell's stated policy opposition to military action in Syria. But as we've written in this space, it's impossible to view the mechanics of big debates (like this one) in Washington without also taking the political implications into account.
And for McConnell, the political implications are unique when compared to Pelosi, Reid, and Boehner. In short, he would have had everything to lose and really nothing to gain by supporting a military strike.
As we wrote last week when McConnell was still on the fence even as other leaders agreed to support Obama's call for force, the Republican faces a primary challenger who opposes military action. Supporting a strike would have stoked tensions in the campaign, and it would have positioned McConnell closer to Obama. Strike one.
What's more, it would have put him at odds with fellow Kentucky Republican Sen. Rand Paul (R-Ky.), who has been the voice and face of the opposition movement on Capitol Hill. (Paul is even set to speak on Syria after President Obama does Tuesday night).
Paul has endorsed McConnell for reelection, and the Republican leader is counting on that support to boost his standing among the conservative voters who adore the freshman senator but are skeptical of him. Going against Paul on this issue wouldn't exactly inspire his loyalists to line up behind McConnell. Strike two.
Finally, public opinion about the prospect of an attack has become crystal clear in the last week, with survey after survey showing Americans opposed to a strike. And within the upper chamber, passage is looking ever more uncertain, as three dozen senators are either "no" or leaning "no" right now. Supporting the measure would put McConnell on the wrong side of the debate nationally, and in an shaky part of the smaller universe of the Senate. Strike three.
Of course, going against the grain of the broader public is something Reid, Pelosi, and Boehner will have to come to terms with, too. And for Boehner, who has faced great difficulty corralling votes in his own conference, his stance threatens to further alienate some rank and file Republicans.
But none of the other three leaders are being threatened by primary challengers or are under the electoral microscope the way McConnell is this cycle. Faced with a 2014 map with few pick-up opportunities, Senate Democrats have made McConnell their top GOP target, recruiting secretary of state Alison Lundergan Grimes (D) to challenge him. Pelosi and Boehner aren't at any risk of losing their seats next year, and Reid doesn't face reelection until 2016.
The political implications for McConnell are much more personal and more immediate.