AAN has invested in several million-dollar national campaigns supporting large numbers of Republican incumbents, including a $1.2 million effort announced on Monday, but nothing as focused as what Patriot Majority USA and Center Forward have done to help a few Democrats over the past month. There are certainly exceptions - one is Rep. Tom Latham, R-Iowa, who got some early help from Crossroads GPS for his member-versus-member matchup against Democratic Rep. Leonard Boswell. Part of the reason could be that a lot of the most vulnerable GOP members, like Illinois Rep. Robert Dold, are in expensive media markets where it is difficult to get bang for your buck.
Also, this could all change tomorrow. GOP groups are going to flood the House landscape with TV ads again this cycle. But so far, it appears that Democratic issue advocacy groups have been quicker to boost their most vulnerable incumbents on TV, perhaps to try to inoculate them against a certain flood of attack ads later this cycle.