Trumpism, it turns out, is contagious.

Trumpism is an ailment that draws its name from former President Donald Trump. The disease’s symptoms are that the victims suffer from the delusion that the unwritten rules that govern American politics don’t apply to them, that they somehow can win elections without ever persuading anyone who didn’t already completely agree with them.

The latest to suffer from the illness is one of Trump’s rivals for the 2024 Republican presidential nomination, Florida Gov. Ron DeSantis.

Not long ago, DeSantis seemed like one of the hottest political properties around.

He was touted as the all-but-inevitable successor as GOP leader to Trump, the Republican who had the best chance of beating President Joe Biden in a presidential election. His poll numbers looked solid—in some head-to-head tests with Trump, DeSantis ran close to the former president. Big donors who wanted the goodies a Republican president could deliver—lower taxes on non-labor-derived earnings and wealth and more deregulation—but who had grown tired of Trump’s dysfunctional, crisis-a-day style of governing flocked to the Florida governor.

That was then.

This is now.

Now, DeSantis trails Trump by at least 30 points in most polls. Instead of separating himself from the pack and turning the primaries into a mano-a-mano contest with the former president, DeSantis has settled back among the pack. He’s even begun to feel other Republican contenders—former New Jersey Gov. Chris Christie, for example—nipping at his heels in certain key early primary states.

Worse, DeSantis has spent much of his war chest and has discovered that fresh donors are hard to come by. The folks who can write big checks and host lavish fundraisers like back frontrunners, not competitors who stumble getting out of the gate.

What prompted DeSantis’ tumble?

Well, he succumbed to the same fever that has bedeviled Trump and his rabid but diminishing band of followers.

Politics, the adage goes, is a matter of addition, not subtraction. Successful politicians find areas of common ground and common interest, then use them to forge alliances and expand the support necessary to win elections and get things done in a self-governing society.

This means that points of disagreement often are de-emphasized or set aside for later days after the items on the wish list political allies have in common have been secured.

But that never has been Trump’s way.

Because he sees the world exclusively in binary terms—one is either with him on everything or against him, with no in-between—the former president devotes an inordinate amount of time to convincing those who otherwise would work with him on some issues that they have no place in his camp.

His record demonstrates as much.

In 2016, the one race he won, Trump lost the popular vote by nearly 3 million ballots. In the midterms two years later, when he made the congressional races an up-or-down referendum on his chaotic presidency, he increased that deficit to 10 million votes. In the 2020 presidential election, he came up 7 million short in the popular vote tally.

Worse, there were signs that he had managed to alienate suburban voters—once a strong source of support for the GOP—for years to come. Every Trump-backed candidate in a battleground state went down to defeat.

Trump accomplished these dubious achievements by focusing all his attention on satisfying his base—and ignoring or insulting anyone who wasn’t willing to shout “amen” to his every pronouncement, even if that person voted with him more than 90% of the time.

DeSantis should have taken steps to avoid infection with Trumpism.

Instead, he embraced the virus.

Ignoring the reality that much of his financial support came from big business, DeSantis picked and escalated a stupid fight with Disney. Not mindful that almost every business owner in America is on a desperate quest for qualified labor, he released a gay-baiting campaign ad that told all workers who aren’t white, straight, and evangelical that they didn’t belong in a DeSantis-led society.

That’s what Trumpism does.

It deludes the sufferer into thinking that subtraction is addition—that one can win elections by telling large numbers of people to go vote for someone else.

The sad part of all this is that Trumpism seems to have no known vaccine or cure.

Once politicians get sick with it, they stay sick.

Just ask Rudy Giuliani.