re: And you criticize the Democrats for Lieberman.
You're drifting into the stratosphere again.
Lieberman didn't switch to Republican. He ran in his primary, was destroyed by national Democratic Party opposition in that primary, then ran as an independent and beat the other two candidates. Lieberman is still in the Democratic caucus.
Specter changed parties because unlike Lieberman's state, a primary loser in Pennsylvania can't run as an independent. It's that simple.
He wants to keep his job, and would probably run as a Whig if that gave him the best chance at keeping a seat.