This one's gotta hurt. Earlier today, NARAL Pro-Choice America endorsed Joe Sestak over Arlen Specter. The endorsement comes with a $5,000 campaign contribution, but the real value may be in having president Nancy Keenan say this:

"Many Pennsylvanians are under the impression that Arlen Specter might be a reliable pro-choice voice, but his record says otherwise. Pennsylvanians deserve a senator who considers being pro-chioce a position of conviction, rather than a position of convenience."

While the release describes Specter as having been "once a consistent supporter of choice," it faults him for supporting Bush Administration Supreme Court nominees Samuel Alito and John Roberts.

"This race is at a critical juncture, with many primary voters still undecided," Keenan says. "We want pro-choice voters in the Democratic primary to know that, without question, Joe Sestak is the candidate who is best positioned to defeat an anti-chioce opponent in the November general election."

This shouldn't come as too big of a surprise: NARAL endorsed Specter's Democratic rival back in 2004, Joe Hoeffel, despite backing Specter in 1998. (Can anyone name Specter's Democratic rival that year without using Google? I sure couldn't.)  

Specter, meanwhile, is getting support from the Democratic Senatorial Campaign Committee. Which, as Greg Sargent points out, means the party is now spending to protect a former Republican against a longtime Democrat. 

As for Sestak, he's launched a Web ad of his own, which makes a somewhat  convoluted attempt at following Arlen Specter's convoluted career. The ad pairs footage of Barack Obama praising Specter with footage of Specter being backed by George Bush ... or saying he voted for John McCain. It shows Obama praising Specter for voting for the stimulus bill ... and follows that up with Rick Santorum praising Specter for backing the Bush tax cuts. 

Things get a little muddled in there, but I guess that's the point.