His rival Vivek Ramaswamy responded that Mr. Trump was “the best president of the 21st century.” A sleepy debate had yielded to a gloves-off battle over the future of the Republican Party.

The elephant in the room isn’t even in the room. Some of the early polls in primary states suggest that Republican voters are actually open to considering a candidate other than Trump.

Despite the Republican National Committee’s accommodating efforts to move the third debate from Alabama to Florida in hopes the closer proximity to Mar-a-Lago would encourage Trump to ...