President Trump’s simmering feud with the governor of Florida, Ron DeSantis, is coming to a full boil over their divergent positions on the Colorado Senate race.

Mr. DeSantis has been touted as the successor leader of Mr. Trump’s political movement, with many seeing him being able to sustain the appeal of Mr. Trump without the personal and legal baggage that accompanies the former president.

Mr. DeSantis was elected to the House in 2012, where he made a name for himself as a founding member of the House Freedom Caucus and as an ally to Mr. Trump.

In 2018, Mr. DeSantis launched his bid for governor, which was considered something of a long shot until he received Mr. Trump’s endorsement. The nod catapulted him into a narrow victory in the race.

Since then, Mr. Trump has frequently taken credit for Mr. DeSantis’s rise in politics. More recently, however, he has reportedly grown resentful of the attention lavished on Mr. DeSantis and the whispers about his potential as a 2024 presidential contender.

This battle remained largely out of sight until the recent release of a book by a New York Times reporter, Maggie Haberman. She reports that Mr. Trump called Mr. DeSantis “fat, phony, and whiny” over the course of their interviews for the book, and the former president accused him of copying Mr. Trump’s body language and personal style.

While the anecdotes gave color to the relationship between Messrs. Trump and DeSantis, their personal distaste for each other had not yet led to open conflict.

That all changed Sunday night, after the two Republican heavyweights’ opposing positions on the Colorado Senate race became clear.

The Republican nominee, businessman Joe O’Dea, publicly broke with Mr. Trump early in the campaign, saying that the country was ready to move on from him. Mr. O’Dea said he would not support a 2024 presidential bid by the former president, and might even actively campaign against him.

Mr. Trump responded to Mr. O’Dea’s snub with a statement on Truth Social reading, “MAGA doesn’t Vote for stupid people with big mouths. Good luck Joe.”

Over the weekend, Mr. DeSantis endorsed Mr. O’Dea, going so far as to record an automated phone call saying, “I’ve watched Joe from a distance and I’m impressed.”

Mr. Trump, late Sunday, called the endorsement by Mr. DeSantis “A BIG MISTAKE.” He has remained silent on the topic since.

Many believe a public spat with Mr. Trump is one of the few things that could sink Mr. DeSantis’s image within the Republican Party.

In August, the director of the University of North Florida’s Public Opinion Research Lab, Michael Binder, warned that Mr. DeSantis “rightfully should be concerned because all it takes is one little nickname, and no one is better at making them stick than Trump.” 

The public conflict between Messrs. Trump and DeSantis comes as Republican voters show some signs that they may prefer the Florida governor to lead the GOP in the coming years.

An ABC News/Ipsos poll released Monday found that 72 percent of Republicans believe Mr. DeSantis should have a “great deal” of influence over the party’s future, while only 64 percent say the same of Mr. Trump.

In the same poll, 63 percent of Republicans said that Senator Cruz should influence the direction of the party moving forward while 52 percent said the same of Senator Scott.

Other polls suggest that Mr. Trump would lead a Republican field in a presidential primary, with a Quinnipiac poll released in late October finding that some 78 percent of Republicans want to see him run in 2024, up from 66 percent in May.