E.J. Dionne: Democrats finally realized who their real opponent is

Washington • After spending the first half-hour of Thursday’s debate tearing each other apart over health care — which happens to be their party’s strongest issue — the Democratic presidential candidates realized that their opponent is Donald Trump and acted accordingly.As a result, despite jabs and disagreements throughout a three-hour marathon, they offered a far less divisive performance than they (and an additional 10 contenders) turned in during the first two de