Another PA12 postmortem, this time from the NBC political team in the NYT.

Come November, Republicans’ ability to win in these types of districts and against these types of candidates could very well be the difference between picking up 25 seats (a good showing, but near the historical average for the opposition party in a president’s first midterm cycle) and 40-plus seats (which would make John Boehner, Republican of Ohio, the next House speaker).

Message also matters. In this race, the Republican campaign against Mr. Critz was all over the place. Republicans and right-leaning interest groups tied him to President Obama and House Speaker Nancy Pelosi; they tried to associate him with the Democrats’ health care reform, even though he opposed it; and they attempted to link Mr. Critz, a former Murtha aide, to ethical allegations involving his old boss.

By contrast, Mr. Critz and the Democrats had a relatively consistent message — they portrayed Mr. Burns, a millionaire businessman, as out of touch with Pennsylvanians, and Mr. Critz as someone who would deliver for the district. In short, while Republicans were trying to nationalize the race, Democrats localized it.

Finally, because special elections are usually mad dashes to fill vacant seats, organization plays a key role. The political parties must quickly find candidates, build campaigns and turn out the vote.

In Pennsylvania’s 12th, Democrats simply had the better operation.