Perhaps the most unpersuasive spin on the PA-12 race I have seen comes from John McCormack:

The only competitive statewide primary Tuesday was on the Democratic side, and that helped boost Democratic turnout (Dems outnumbered Republicans 2 to 1 at the polls in PA-12). That advantage will be gone in the fall. Critz ran as a conservative Democrat–his ads portrayed him as a pro-life, pro-2nd Amendment, anti-cap & trade candidate, who would have voted against Obamacare. That’s an advantage many Democratic incumbents in GOP-leaning districts won’t have in November. Their voting records will tell a different story.

I keep seeing references to the “Sestak effect” to explain why Critz won, as if it is a one-time fluke that Joe Sestak was on the ballot yesterday and this will never be repeated. In the fall, Sestak will be facing Pat Toomey in the general election, and it is far from certain that Toomey is going to win a statewide race in a state that has been trending Democratic and where the Republican Party’s numbers have been shrinking in recent years. This race will be a high-profile contest and both parties are going to be making significant efforts to get out the vote. All other things being equal, that probably gives the edge to Sestak. With Sestak on the ballot again in the fall, many of the people who turned out for Critz yesterday will likely show up again. Indeed, probably more Democratic voters will show up in PA-12 for the general election than in the primary, which would reinforce Critz’s advantages. This increase isn’t some kind of trick: turnout always goes up in the general election.

It’s true that Critz campaigned against many of the major legislative items supported by his party’s leadership. Dozens of Blue Dogs in the Democratic conference actually voted against these items. These are mostly the same House members in the most vulnerable seats. There are some genuinely vulnerable Democrats, such as Harry Teague in NM-02, who voted for cap-and-trade. Teague represents the major oil-producing region of our state, so he is going to have a very hard time winning re-election, but there aren’t that many Blue Dogs like Harry Teague. There were 44 Democratic nay votes on that bill, and among them one finds some of the most vulnerable conservative Democrat incumbents: Arcuri, Bright, Childers, Foster, Nye, as well as now-defeated or retired incumbents such as Mollohan, Tanner, and Berry whose replacements are unlikely to identify closely with the administration’s agenda. Indeed, the new West Virginia Democratic nominee Oliverio is even more relatively conservative than was Mollohan. Many of the Blue Dogs likewise voted against the health care bill. Bright, Childers, Kratovil, Markey, Teague, and Minnick were among the nay votes. There are nine Democratic incumbents right there that can credibly distance themselves from Obama and their party leadership as necessary, and they are among the twenty most-vulnerable incumbents. If they can protect themselves against a backlash by campaigning as Critz did, that takes away some of the most promising targets for Republican pick-ups.

There are Democratic incumbents that have put themselves on the wrong side of their district’s voters with some important votes, but there are not as many of them as some on the right seem to think and there are not nearly enough to facilitate a Republican takeover.