How will Arlen Specter, the Republican-cum-Democratic senator from Pennsylvania, fare in next year’s Senate election?

The political situation in Pennsylvania and the historical evidence suggest that Specter, who has the backing of the White House and the Democratic Senatorial Campaign Committee, is heavily favored to win the Democratic primary in 13 months and also has the edge in a prospective general election against Republican former Rep. Patrick J. Toomey, who had been challenging Specter in the GOP primary.

Robin Kolodny, a political scientist from Temple University in Philadelphia, told CQ Politics by e-mail that “voters don’t usually punish party-switchers much.”