"Americans for Prosperity, a group financed in part by the billionaire Koch brothers, has spent an estimated $20 million on television advertising that calls out House and Senate Democrats by name for their support of the Affordable Care Act. The unusually aggressive early run of television ads, which has been supplemented by other conservative initiatives, has gone largely unanswered, and strategists in both parties agree it is taking a toll on its targets." Carl Hulse in The New York Times.