It's official, at least reportedly: Sen. Arlen Specter, R-Pa., will have a primary challenger. Former Rep. Pat Toomey, a conservative who heads the Club for Growth, is said to have decided to run against Specter for a second time. The first time he challenged the incumbent, Toomey lost by about 17,000 votes, or a little more than one percentage point.
Toomey could win the primary this time, though ultimately that might not really matter. It's difficult to believe he could win a general election, in contrast to Specter, who does have enough Democratic support that he could pull off a victory pretty easily if he didn't have to deal with a challenge from within his own party. A heated primary race, however, will take quite a bit out of him and his fundraising ability and leave him vulnerable in the general.
In some ways, this race -- if it does indeed happen -- is analogous to the primary campaign Ned Lamont waged against Sen. Joe Lieberman, I-Conn., back in 2006. In both cases, grassroots activists from the base of the party are upset with a longtime incumbnt for acting in a manner inconsistent with their beliefs. The key difference, though, is that if Lieberman had not run as an independent after losing the Democratic primary, Lamont would have been all but assured victory. That's not the case for Toomey.