When your mind runs over the history of the Grand Old Party, you think of the presidents first. You think of Abraham Lincoln and are proud to be in some way associated with a political party whose first president was our greatest. You recall Ulysses S. Grant and Theodore Roosevelt and Calvin Coolidge, and you think .  .  . not bad, not bad at all. And you move along to Dwight Eisenhower and Ronald Reagan and the two George Bushes, and you conclude: It’s an impressive legacy.

Who knows whether President Donald Trump will ever be looked back on with comparable nostalgia and respect? If he is, we suspect it will be due mostly to the actions of Republican members of Congress. It won’t primarily be due to their diligence in supporting him. What will prove more important to success for the Republican party and for Republican principles over the next four years is the success of Republicans in Congress in guiding Trump, in correcting him, in checking him—and, yes, at times in opposing him.