Jay Cost does some back-of-the-envelope math. How does having a bona fide conservative in the race make the Senate more Democratic probability-wise? Simple: In a blue-purple state like Pennsylvania, Toomey’s a much harder sale in the general election than the incumbent Specter is. If, as seems likely, he knocks Specter off in the primary, the Dems will be staring at a fairly easy pick-up, especially if The One descends from Mt. Olympus to do some campaigning for the nominee. We’ve gamed this out before but follow the link and check Cost’s assumptions. Is it time for the blogosphere to catch … Spectermania?

One thing to bear in mind as you mull: It’s not worth fretting overly much about the Democrats getting to 60 because of this, as that already seems assured by the fact that Bunning’s a dead man walking in Kentucky. Here’s Specter on MSNBC this morning proving how worried he is already about Toomey by, er, comparing him to the people at AIG who received bonuses. Skip ahead to the end for that or else watch from the beginning to hear him explain how Obama’s not seeking nuclear disarmament even though The One explicitly called for “a world without nuclear weapons” in Prague. If you figure out what he means when he says reducing our stockpile would be helpful somehow while rogue states are building nukes of their own, shoot us an e-mail. I’d love to know.