The other Republican candidates’ chances of stopping Donald Trump look marginally better today than they did on Friday. Trump won just two of five contests over the weekend and only 30 percent of delegates. Trump remains the front-runner, however, having won 43 percent of the delegates overall among the 20 states and territories to have voted so far. Although that’s short of a majority, Trump will have a chance to improve on his pace as the calendar turns toward states that have more aggressive delegate allocation methods — especially winner-take-all Florida and Ohio, which vote March 15. If Trump wins...