Crossroads GPS, an independent expenditure PAC often linked with Karl Rove, is entering two California congressional races. They've purchased $895,000 in TV air time to back Republican Doug Ose in CA-7 and $705,000 to back Republican Carl DeMaio in CA-52. While those sound like large expenditures, the two districts are in expensive media markets, Sacramento and San Diego. So those investments might not be that much. The reasons for the district choices seem pretty clear. These are expected to be the two best pick-up opportunities for Republicans. I don't think they'll be the two closest, however, since I think that DeMaio will win by more than either candidate does in CA-26. DeMaio is also much better financed than other Republican challengers. So he probably needs the money less. That said, he's going up against a deep-pocketed Democrat and Republicans were certainly overconfident in 2012.
In the 2012 election, I believe there were seven different independent expenditure groups active in CA-7 and there were several in CA-52. So don't expect this to be the last of the outside money pouring into the races.