The Republican attack operation, Crossroads GPS, led in part by Karl Rove, has had a difficult time over the last month or so.

A few weeks ago, for example, a Montana station pulled a Crossroads ad that misled the public. Rove’s outfit was also caught blatantly lying about former President Bill Clinton, then got caught pushing obviously bogus claims in Massachusetts, then got caught making even more demonstrably false claims about former Gov. Tim Kaine (D), running in a competitive U.S. Senate race in Virginia.

But the new Crossroads lie is easily the funniest. Greg Sargent has a report today on a Crossroads attack ad targeting Elizabeth Warren that’s almost hard to believe.

A few weeks ago, the Rove-founded Crossroads GPS spent six figures on an ad that was all about Occupy Wall Street, falsely insinuating that Warren supports protesters’ violence and slamming the protests for advocating “radical redistribution of wealth.”

Today, with Warren edging into a lead over Scott Brown, Crossroads GPS is out with a new spot that doesn’t mention Occupy Wall Street at all, and actually tars Warren as too cozy with the big banks at the expense of the middle class.

I wish this were a joke. In early November, Rove’s attack operation wanted voters to believe Warren was in league with radical, violent leftists. In early December, Rove’s attack operation now wants voters to believe Warren was in league with Wall Street, handing out TARP checks to fat-cat bankers.

There are a few lessons to take from this. First, given the recent track record, I don’t think it’s the least bit unreasonable to start characterizing Crossroads GPS as less of an “advocacy organization” and more a group of professional liars. Objectively, that’s what they do.

Second, Rove and his cohorts really do believe voters are idiots.

Third, Warren clearly scares the hell out of Rove and his financiers, enough that they’re already prepared to throw the kitchen sink at her, even if it leads to incoherent, obviously-ridiculous smears.

And finally, if this ad is a sign of things to come, and 2012 comes down to which side of the political divide is too close to the Wall Street elite, Republicans are in for a very long, unsuccessful year.

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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.