An interesting window into the politics of the Obama administration’s war in Libya may open this week, when Senators Kay Bailey Hutchison (R-TX) and Joe Manchin (D-WV) reintroduce a resolution expressing the sense of the Senate “that it is not in the vital interests of the United States to intervene militarily in Libya,” and calling on NATO member states and the Arab League, two parties who are directly threatened by the violence in Libya, to provide the necessary assets to the mission.

Such resolutions almost never have a direct impact on the conduct of military operations. Hutchison-Manchin isn’t even the first attempt to constrain President Obama’s ability to wage war in Libya. A resolution offered by freshman Senators Rand Paul (R-KY), and cosponsored by Mike Lee (R-UT), went well beyond the question of whether the war advanced vital U.S. national interests, and attempted to reassert the legislature’s control over the warpowers generally. Borrowing from something that then-Senator Barack Obama said in 2007, the resolution read “The president does not have power under the Constitution to unilaterally authorize a military attack in a situation that does not involve stopping an actual or imminent threat to the nation.” This language, which likely strikes most Americans as eminently sensible, managed to garner just 10 votes, all from Republicans.

Still, the prospect of a vote on a much narrower resolution must worry the war’s advocates. At a minimum, an up or down vote on Libya will test the strength of the still-vocal interventionist caucus in the U.S. Senate.

These reliably pro-war members took to the Sunday shows to make the case for escalation. On CNN’s State of the Union, Sen. Lindsey Graham called on the Obama administration “to cut the head of the snake off. Go to Tripoli [and] start bombing Qaddafi's inner circle.” Worries that the uprising might provide cover for al-Qaeda to expand its operations in the Maghreb were unfounded, John McCain asserted. McCain’s long-time friend Sen. Joseph Lieberman agreed, explaining on the same program, “We're in the fight and the political goal is to get Qaddafi out and to help the freedom fighters achieve their own independent Libya. You can't get into a fight with one foot. You got to get into it.”

How many others in the Senate subscribe to the interventionists’ interpretation of what America’s role in Libya should be is unclear. I have never understood why Republicans would scramble to follow foreign policy advice from a Democrat, and Al Gore’s running mate, no less. Senators McCain and Graham hold more sway among their GOP colleagues, but their outspoken support for a number of other ill-considered ventures, including especially the war in Iraq, likely gives pause to some. Graham’s fellow South Carolinian Jim DeMint, for example, voted in favor of the Paul-Lee resolution, and has otherwise shown no great enthusiasm for adding to the U.S. military’s already full plate. The Boston Globe’s Theo Emery reports today that Massachusetts Senator Scott Brown isn’t yet ready to endorse an escalation of the war. Meanwhile, Maine’s Susan Collins told Emery that the U.S. military’s role in Libya should be limited to intelligence, logistics and other capabilities that U.S. allies lack.

Who else might vote for Hutchison-Manchin? Presumably those within the Democratic caucus who still think that war is generally a bad thing, even when it is waged by a Democratic president. No Democrat voted for Paul-Lee, but Senator Manchin’s co-sponsorship of this much more narrowly worded resolution should provide cover for centrists, as well as progressives who once reliably opposed wars of choice.

One thing is clear with respect to the war in Libya: politics favors the skeptics. There is no groundswell of public opinion calling for yet another armed nation-building mission in a strategic backwater. Though the costs of the war are small relative to the gargantuan military budget, most Americans can be counted on to oppose wars that do not clearly advance U.S. national security interests, regardless of how much or how little they cost. They are doubly skeptical given that the costs of the wars in Iraq and Afghanistan have vastly exceeded even the most pessimistic of predictions, and have not delivered the security that the advocates for war claimed.

It is a truism that politics doesn’t generally drive foreign policy. People who celebrate America’s role as the world’s policeman don’t expect to reap great political rewards for taking such an unpopular stand. McCain, Graham and Lieberman have always stood apart in that regard. Recall, for example, that John McCain bragged that he would rather lose an election than lose a war. He never appeared to consider that both eventualities were possible. Perhaps some of his fellow senators will.