The McCain campaign just released a new ad entitled “Obama Praising McCain,” which focuses on Barack Obama’s past praise for the global warming bill that McCain authored with Joe Lieberman (I-Conn.).

It features this remark from Obama, at a hearing of the Environment and Public Works Committee in January 2007: “The right approach begins with the proposal put forward by Senator Lieberman and Senator McCain. The Lieberman-McCain bill establishes limits for greenhouse gas emissions. It’s a framework that’s not only good for the environment, it’s also good for business.”

So is the ad attacking Obama for agreeing with McCain? Promoting McCain’s ability to work across the aisle? Obama said on Wednesday that he would want to work with McCain on global warming post-election, regardless of who wins. In a speech in Des Moines, Iowa, he had this to say about the new ad:

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Just this morning, the McCain campaign put out an ad that showed me praising him and Senator Lieberman for their work on global warming -– as if there’s something wrong with acknowledging when an opponent has said or done something that makes sense. I think we need more of that in Washington. I don’t disagree with Senator McCain on everything, and I respect his occasional displays of independence.