When Pat Toomey announced that he'd be challenging Sen. Arlen Specter in the Pennsylvania primary, we were prepared for Specter to tack to his right. And he did just that. After ushering forward and voting for the stimulus spending package, Specter voted for a Republican alternative budget that would have frozen spending. He announced his intent to oppose EFCA. And he withheld support from President Obama's OLC-chief designate Dawn Johnsen.

But then he ditched the Republican party and, with it, much of the incentive to do the bidding of conservatives. At about noon, he became a Democrat. At about 2:15, in a move that vexed liberals, he announced that he doesn't support Dawn Johnsen. A few hours later he voted to confirm the supposedly controversial Kathleen Sebelius to be Secretary of the Department of Health and Human Services. This morning he appeared with Obama and other Democrats in a celebratory photo-op at the White House.

And tonight, he'll have another test.

The Senate will vote on the final budget shortly. In a previous incarnation, Specter voted against it. This evening, in an early test, he'll have to decide whether to stick with that judgment, please the party faithful and vote with the Democrats, or somehow abstain. Check back here for the final tally.