Former GOP Sen. Arlen Specter, in the face of polls that had him 20 points behind a conservative challenger, is now the newest Democratic member of the US Senate. This is significant for all sorts of reasons, not least of which he would be the 60th (and filibuster-proof) vote. As for us green-minded folk, with climate change legislation subject to filibuster, having Specter a Democrat suddenly makes the possibility of passage more than a pipe dream. While you could certainly argue that Specter won't vote for cap-and-trade even as a Democrat (especially with coal-producing Pennsylvania as his constituency), you can hope he displays the passion of the newly converted, as past party-switchers often have. As Matt Yglesias summed up the question, "Will he vote like a northeastern Democrat, or will he vote like Ben Nelson?" The good news: Pennsylvania is no Nebraska. With Dem Governor Ed Rendell and Dem Sen. Bob Casey breathing down his neck (and with the need to prove his chops to his new Democratic voters) Arlen has every reason to walk the Democratic walk.
[Updated 4:45pm]: Dave Roberts at Grist digs into the climate legislation implications of Specter's jump. Nutshell: He'll still vote against. I think that underplays the windblown nature of Sen. Specter. Right now, it's true that he can't be considered a supporter of something like the House climate legislation. On the other hand, as Dave points out, a need to tack left to fend off a Democratic primary challenge is always a possibility. But his vote will also depend on just how lucrative to the carbon-heavy states the Dems make the climate bill. Predominantly, this is about getting Midwestern Dems on board, but the calculus is the same for PA. If they focus investment and/or tax rebates in a particularly attractive way on coal-dependent states, I don't think it would be beyond Arlen to flip-flop and support cloture (at a minimum).