Republicans will see these tactics again this fall. Democrats seem convinced ObamaCare is an opportunity, in the words of Ms. Sink’s pollster Geoff Garin, “to play offense, and not just defense,” with criticism “at least as potent, if not more potent, than the attacks.” However, unlike Ms. Sink, Democratic incumbents voted for ObamaCare and made promises that turned out to be untrue, making them far more vulnerable than she was.

Mr. Jolly put ObamaCare in a larger frame, urging voters to elect someone to be a check and balance for Mr. Obama, rather than blindly support him. This cut well with independents, according to some private polls by outside groups. Mr. Jolly’s success depended upon convincing them he would go to Washington to make things work, not to blow it up.

The Republican campaign also understood that Ms. Sink’s record mattered. GOP ads pointed out that as president of NationsBank (now Bank of America BAC +0.06% ) in Florida, she collected $8 million in salary and bonuses while thousands of bank jobs were cut. Ads also noted that as Florida’s chief financial officer Ms. Sink approved lucrative contracts with her former bank, and that Florida’s pension funds lost billions between 2007 and 2010.