John McCain makes the usual alarmist noises on the Syria resolution vote:

Sen. John McCain (R-Ariz.) said Monday that it would be “catastrophic” if a use-of-force resolution against Syria fails to pass Congress.

“A rejection of this resolution would be catastrophic, not just for him but for the institution of the presidency and the credibility of the United States,” McCain said after meeting with President Barack Obama.

McCain is almost entirely wrong about this. Because so much of the Syria debate has unfortunately become mired in nonsensical arguments about credibility up to this point, it’s important to spell out what the consequences of a Congressional rejection of an attack on Syria would most likely be. If the resolution is defeated, what would other governments conclude about U.S. readiness to back up its other security commitments? It seems reasonable that they would conclude that the U.S. isn’t going to go to war to back up vaguely-worded, off-the-cuff threats that the president issued in response to another country’s civil war. How many other U.S. security commitments fit that description? Fortunately, the correct answer is none. Which U.S. interests or allies will genuinely be more at risk in the days and weeks after the Syria resolution fails? The truth is that defeating a Syria AUMF resolution doesn’t undermine any other U.S. commitment overseas.

The domestic consequences may be more significant, but to the extent that they impose limits on presidential action they are only undesirable for those wedded to the idea that the executive should have virtually unconstrained power to wage war around the world. Future presidents may still be able to get away with launching military strikes without Congressional approval, but this episode will make it a little more difficult for them to assert Congress’ irrelevance without facing some resistance. How much resistance future presidents face will be up to future members of Congress, and the precedent of going to Congress on Syria will be weighed against counter-examples (e.g., Kosovo, Libya) when presidents bypassed Congress entirely without suffering any consequences. Of course, all of this hinges on Obama’s willingness to abide by Congress’ decision.

McCain probably knows that a no vote isn’t as “catastrophic” as he claims, which is why he is willing to vote against a resolution that doesn’t go far enough in dragging the U.S. into a new war:

McCain will only support a resolution “that will achieve the goals that I just described,” he said on TODAY. “If it doesn’t, then obviously I can’t support it.”