Super Tuesday II didn’t so much yield results as reveal continuing trends. Donald Trump up, Hillary Clinton up.

This is what I hear from Washington’s Republican political leaders and operatives: Wait and see. There’s still time for Mr. Trump to self-destruct, for voters to start to see through him. In the meantime, get all the delegate-selection rules, all the names and contact points for every delegate picked so far. If we have to fight it on the floor, we fight it on the floor. Or, more delightfully for sentimentalists,...