THEY THOUGHT IT WAS CONSTITUTIONAL BEFORE THEY DIDN’T…. Yesterday afternoon, Senate Republicans aggressively pushed a measure to challenge the constitutionality of the individual mandate in health care reform.

The constitutional point of order, authored by Sens. Jim DeMint (R-S.C.) and John Ensign (R-Nev.), was defeated on a 60-39 vote, with Sen. Jim Bunning (R-Ky.) not voting. DeMint and Ensign argued the Reid bill would force citizens to purchase health care — which they said goes beyond the federal government’s authority.

Maybe you approve of the mandate; maybe you don’t. Let’s put that aside for a moment. What’s interesting about yesterday’s vote goes beyond the merit of the specific provision.

Sen. Olympia Snowe (R-Maine), for example, voted yesterday to declare an individual mandate unconstitutional. Just two months ago, she voted for a Democratic health care reform plan … which included the same individual mandate. How can a provision be permissible in October but unconstitutional in December?

Sen. Chuck Grassley (R-Iowa) also voted yesterday to declare an individual mandate unconstitutional. Over the summer, he told Fox News, “I believe that there is a bipartisan consensus to have individual mandates…. There isn’t anything wrong with it.”

Sens. Lamar Alexander (R-Tenn.), Bob Bennett (R-Utah), Mike Crapo (R-Idaho), Lindsey Graham (R-S.C.), and Judd Gregg (R-N.H.) all voted yesterday to declare an individual mandate unconstitutional. All five of them are on record co-sponsoring a reform measure that included an individual mandate.

The point here is not just to highlight the bizarre inconsistencies of Republican opponents of health care reform. This is also important in realizing why bipartisanship on health care proved impossible this year — Republicans were willing to reject measures they’d already embraced. All the Democratic outreach and compromise options in the world can’t overcome the fundamental lack of seriousness that comes with a party that opposes and supports the same idea at the same time.

Post Script: In case there’s any lingering confusion, by the way, the notion that an individual mandate violates the Constitution — an argument suddenly embraced by the entire Senate Republican caucus — is absurd. As Ezra Klein explained in November, “[Y]es, the individual mandate is constitutional. For a roundup of the argument, see this Tim Noah piece. For a longer, more technical explanation, see this post by law professor Mark A. Hall. The summary is that you can look at the individual mandate as a tax, which is constitutional, or as a regulation forcing private actors to engage in a certain transaction, much like the minimum wage, which is also constitutional. I’ve also heard scholars mention auto insurance, which is an obvious analogue, and the Americans With Disabilities Act, which proved that the government can order businesses to install ramps, despite the fact that the constitution doesn’t explicitly give the federal government jurisdiction over entryways.”

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.