Gore Vidal remarked during the George W. Bush years that comedians such as Jon Stewart had become leading political figures because the Left lacked powerful alternative voices. The idea that late-night clowns could represent American liberalism struck the great author as an absurdity.

Ahead of the final episode of “The Late Show With Stephen Colbert” on Thursday night, President Donald Trump was asked by a reporter if he had something to say about the host and his show. In reply,