If there is any issue on which members of the GOP are united it is Obamacare. Gallup recently found that 86% of Republicans disapprove of the law. Yet Donald Trump has just won two GOP primaries despite his support of its worst provisions. Before the South Carolina contest, for example, he announced that he favors its universally reviled individual mandate. In New Hampshire, he studiously avoided denouncing the Obamacare Medicaid expansion. Trump claims he will repeal the law but said yesterday that opposition to national health care was part of the problem with Republicans. So, how can he be winning...