Congressional Quarterly's Shira Toeplitz has a good rundown on all the ways in which presumptive Pennsylvania GOP Senate nominee Pat Toomey has moved to the center ever since Arlen Specter bolted for the Democratic Party. Which makes me again wonder whether it was a mistake for Obama to encourage Specter's defection.**

If Obama hadn't welcomed Specter with open arms and Specter had been forced to stay in the GOP, he almost certainly would have lost the Republican primary to Toomey, who planned to run to Specter's right. Even though Toomey would have pivoted to the middle for the general election, the pivot wouldn't have worked terribly well, because he would have already spent months running as an archconservative and would be known to many Pennsylvania voters as such. In other words, the Democratic nominee would have been running against an out-of-the-mainstream-for-Pennsylvania Republican. But now that Toomey's been able to begin his move to the center early, he'll likely be viewed by many general election voters as a legitimate moderate.

Meanwhile, the Democratic primary is shaping up to be a bloody battle between Specter and Joe Sestak. And the idea that, as Politico reports, "Democrats are buoyed by polling that suggests either candidate would run competitively against presumptive Republican nominee Pat Toomey" isn't exactly comforting, when you consider that the only reason Toomey is a formidable candidate is because he didn't have to run as a right-winger in order to win his primary. It's enough to make you think that if Obama had simply taken a hands-off policy toward this race, Democrats would have had a better shot at picking up that Pennsylvania Senate seat in 2010.

**- Of course, Specter's defection has paid short-term benefits for Obama, especially on health care. So, if that was Obama's calculation in encouraging Specter's switch, it was a smart move.