The Fix is reporting that Arlen Specter will switch parties today. Dramatic, but it makes sense: not only is he more philosophically in tune with the liberal party, but as he notes in his statement, some 200,000 Pennsylvania Republicans have recently switched registration to the Democratic Party. Those were “Specter Republicans,” presumably, who turned coat, and without them Specter would have practically no chance of beating Pat Toomey in the GOP primary.

This means 60 Senate seats for the Democrats — nominally a filibuster-proof supermajority, but not really, since filibusters tend not to be along strict party lines. This sorry episode shows what a mess the GOP has become: the GOP is now too ideological to keep the likes of Specter in the party, but not ideological enough to dump them when the moment is ripe (as it was in 2004, when Toomey would have had a shot at winning a general election if the party had jettisoned Specter). The GOP winds up being the party that alienates liberal Republicans and independents, even as it continually sells out conservatives. The result: a rump minority of 40 in the Senate. It’s a perfect recipe for failure, both in strict electoral terms and all the more so in the substantial policy terms that conservatives should care about.