Arlen Specter and the Single Gun Show Theory

I was wondering when or even if the Democratic U.S. Senate primary between the incumbent party-switcher Sen. Arlen Specter and Delco U.S. Rep. Joe Sestak would ever heat up -- both sides are finally running ads, and the conventional wisdon is that Specter, who not long ago was a pro-Bush, pro-Santorum Republican, had skated far enough to the left on most issues like health care to at least beat back the rationale for Sestak's challenge. Maybe so, but there is still room on Specter's left.

Specifically, you can't consider yourself much of a progressive if you're still opposing closing the loophole that allows for purchases without background checks at gun shows, as Specter has done in his Republican past. Some 168 mayors from Pennsylvania are today begging Specter and his fellow anti-gun-control Democrat Sen. Bob Casey to change their minds on this issue, and this seems like one of those cases where good politics would actually be good policy.