Liberal columnists and Democratic strategists have taken to arguing that ObamaCare is working and no longer a political negative, implying that Democratic candidates should tout it on the campaign trail. Republicans should pray they do, assuming the GOP knows how to respond.

As presidential scholar George Edwards III observed in his 2012 book "Overreach," the Affordable Care Act is "perhaps the least popular major domestic policy passed in the last century." It remains so today. A June 3 Fox News poll found...