I agree with this assessment:
Democrats, from the President on down, are trying to get Congressman Joe Sestak to back off, to let Arlen Specter have a free run for the U.S. Senate, as a Democrat from Pennsylvania.
Maybe I’m old-fashioned, but it seems to me that if a sitting U.S. Senator decides to change parties simply because he perceives a better chance of winning reelection–that is, if he does so out of zero personal conviction–then he deserves to be primaried simply for form’s sake, to find out what he actually believes. (Maybe I’m not so old-fashioned: in the 19th century politics being practiced by the Democrats, the bosses decide who runs.)
I’ll note that there was something really irritating and grating about Sestak’s performance the last couple of weeks, but I think he should have the right to run against him in the primary.