For weeks, we heard predictions of a shake-up among President Trump’s advisers. Sure enough, the shake-up came. It just turned out to involve his advisers at Fox News.

The president likes to begin and end his days with a stimulating dose of cable news, especially the warm embrace of Fox. So when Bill O’Reilly reportedly sexually harassed his way out of the No Spin Zone, there were repercussions beyond ratings. Mr. Trump had lost one of his best TV friends.

But the new prime-time Fox News lineup, which debuted on April 24, offers the president and his base something better than friendship: a steady stream of enemies.

Tucker Carlson is a stylistic departure from Mr. O’Reilly, whose 8 p.m. time slot he inherited (after taking over 9 p.m. from Megyn Kelly in January). Mr. O’Reilly cultivated a salt-of-the-earth personal myth, flogging his “working class” upbringing, for instance, though his father was an oil-company accountant.