President Trump has risen three points in Gallup’s Presidential Nominee Favorable Ratings from last month, hitting 50 percent positive. That’s two points higher than Vice President Harris and the first time in his three runs that he’s not underwater. Democrats have little time to accept the reality this reflects, change course, and vanquish their political equivalent of Godzilla.

“Insanity,” a mystery novelist, Rita Mae Brown, wrote in 1983, “is doing the same thing over and over again and expecting different results.” With Trump on the verge of a comeback that has only been accomplished once in American history, Democrats are doubling down on the attacks that have not only failed to stop him; they’ve been unable to halt his rise.

It’s hard to imagine any candidate being stronger after impeachments, indictments, and convictions, much less one making inroads behind the so-called Blue Wall and with loyal Democratic groups like Black men and Hispanics. The obvious answer is to change tactics. Instead, Democrats are taking a page from the Japanese Defense Forces as portrayed in the Godzilla films.

The Japanese fight valiant battles against Godzilla, manning ships, tanks, and jets that have no hope of penetrating his scaly hide. Even nuclear weapons only make the monster stronger, just as every broadside bounces off Trump. Just as fans cheer Godzilla because they know his destruction isn’t real, they cheer Trump because they don’t think he’ll stomp on their house.

As much as Democrats think Americans should see Trump as a monster, threat to democracy, and would-be dictator, those efforts have reached the limits of their persuasive power. Trump has been a fixture of American life for four decades. How people judge him is settled. He was president already and none of the doomsday scenarios that Team Harris paints came to pass.

Expecting that a dark portrayal of Trump’s character will peel off supporters is as doomed as confronting Godzilla with subpoenas. His voters love him, and love is blind. We’ve all tried to tell someone that the person they’re dating is bad for them, only to have them turn on us — and sometimes, our assessment turns out to be wrong, and they have a happy marriage.

Republicans faced a Godzilla with President Clinton. They thought his avoiding the draft, womanizing, untruthfulness, impeachment, and scandals should have been disqualifying. Yet enough Americans looked at him and liked what they saw. He was a bad boy like Trump whose behavior people found alluring.

In 2006, the Liberal Party of Canada learned the same lesson. They debuted a commercial online called “Soldiers,” warning that the Conservative Party leader, Stephen Harper, would put soldiers on the streets. The ad, accompanied by melodramatic music and sinister closeups of Mr. Harper, was mocked even by the left as a farce.

The Liberals wanted Canadians to view Mr. Harper as a fascist. Instead he resembled nothing so much as the young dentist at your local practice, the one who apologizes over and over that “this may hurt a little.” The ad was yanked; Mr. Harper went on to serve ten successful years as prime minister.

Ms. Harris has reached a moment when her attacks are failing to have the intended impact, too. Rather than doubling down on them through Election Day, she can focus instead on policy differences that have proved effective for Democrats in the past: Abortion, social programs, and issues of importance to their core constituents. She can treat Trump not as a monster but as just another Republican.

There will be pushback from Democrats against a change so late in the game. In the Godzilla movies, though, it’s always some freethinkers, considered crackpots by the establishment, that have the courage to innovate and buck the conventional wisdom. They develop new strategies that succeed in delivering a victory where nothing traditional could.

“I want this election to be about something,” Senator Clinton said in September 2016, “not just against somebody.” She couldn’t, though, resist trying to disqualify Trump in the minds of voters. Ms. Harris has little time left to learn the lesson of Ms. Clinton’s defeat and even less to change tactics — to recognize that something new may be her only hope of driving Godzilla back into the sea.