Reihan concludes an otherwise good argument with this odd paragraph:

With Specter running in Pennsylvania’s Democratic primary in 2010, Republicans have a perfect test case. There’s an excellent chance that a primary candidate from the Democratic left will give Specter a serious fight, opening him up to a vigorous challenge from a Republican reformer. That challenge will probably come from Pat Toomey, who, as head of the Club for Growth, has emphasized tax cuts above all else. But as a Senate candidate, Toomey will have to connect with voters in a state hard hit by industrial decline. To have even the remotest chance of winning the seat, he’ll need to offer effective solutions on health care, energy and transportation. This might not come naturally to Toomey. But if he can pull it off, and if he can claim Specter’s scalp, he’ll become the face of a revitalized GOP.

I understand why progressives would be eager to see a primary challenge against Specter, because there are several candidates, chief among them Joe Sestak, who could in all likelihood wipe the floor with Specter if they wanted. Specter has some advantages of incumbency, it’s true, but he doesn’t have the loyalty of the Democratic primary electorate, and a Sestak challenge would be difficult to overcome. (For starters, Sestak has good relations with organized labor, which Specter has lately been opposing on EFCA.) What I don’t understand is why Reihan, or anyone interested in Pat Toomey’s success, believes that Toomey has a better chance against a freshly-minted Democratic nominee such as Sestak than he would against the old, shabby, unprincipled Specter. Specter may still be broadly popular in the state, but his party-switching could be used effectively against him. Long-time Democratic pols have no such liabilities.

Running against Specter, Toomey could run a character campaign–the default option whenever a candidate knows his policies are not well-received by the electorate–and criticize Specter’s defection as proof that he is untrustworthy and unreliable. By contrast, he could then stress his blue-collar background and shared values, and set himself up as the new outsider trying to oust the time-serving establishment hack. “You may not always agree with me, but I’ll keep my promises and you’ll know where I stand”–that sort of thing. Against Sestak, who could probably topple Specter if he ran, Toomey has no chance, and there is no obvious line of attack against Sestak, except, I suppose, to try to make the election a referendum on Obama’s policies, which seems like an automatic loser in a state Obama carried by a wide margin.

Not only would Sestak have an advantage in enthusiasm and turnout, neither of which Specter could count on, but he would also head off any third party challenge from the left that might come about if the general election pitted two pro-war candidates in a heavily antiwar state, as it would if Specter were the Democratic nominee. Sestak has impeccable credentials on national security–he is a retired rear admiral who served as part of the operations in Afghanistan–and he opposed the Iraq war. Even though Pennsylvanians are likely to be much more concerned about domestic matters, a stark contrast between an antiwar former military officer and a pro-war political activist does not work to the Republicans’ advantage. A Sestak-Toomey match-up would be a possibly more lopsided replay of the 2006 results. This is why Toomey’s challenge never made much sense, even if Specter had not flipped to the other side, because in a general election that isn’t against Specter I don’t see how Toomey possibly wins*. His chances are considerably worse against a real Democrat. That being the case, perhaps forcing Specter to jump ship before the primary is all part of a cunning grand strategy to make the Democrats run a badly flawed candidate in a race they would otherwise almost be sure to win. If so, such a strategy would require the Democratic electorate to roll over and accept Specter without much protest, and this is apparently not going to happen.

* The desperate national Republican moves to recruit Tom Ridge or some other Specter-like replacement makes Toomey’s nomination all the more likely, as it was heavy-handed national Republican interference on behalf of Specter five years ago that thwarted Toomey’s run then and enraged conservative activists. Having lost Specter, they cannot now stop Toomey.