Former President Trump blasted Iowa Gov. Kim Reynolds ahead of her expected endorsement of his primary opponent Florida Gov. Ron DeSantis for the 2024 Republican presidential nomination, warning that the move would bring her to "the end of her political career in that MAGA would never support her again."

Reynolds is expected to endorse DeSantis over Trump for the 2024 Republican presidential nomination at a rally in Des Moines on Monday evening. 

"If and when Kim Reynolds of Iowa endorses Ron DeSanctimonious, who is absolutely dying in the polls both in Iowa and Nationwide, it will be the end of her political career in that MAGA would never support her again, just as MAGA will never support DeSanctimonious again," Trump posted. "Two extremely disloyal people getting together is, however, a very beautiful thing to watch."

IOWA GOV. KIM REYNOLDS TO ENDORSE DESANTIS OVER TRUMP, SOURCES SAY

Republican Govs. Kim Reynolds of Iowa and Ron DeSantis of Florida team up in March

Florida Gov. Ron DeSantis speaks at a campaign event with Iowa Gov. Kim Reynolds on Friday, March 10, 2023, in Davenport, Iowa. (AP Photo/Ron Johnson)

He added, "They can now remain loyal to each other because nobody else wants them!!!"

Trump also posted over the weekend that Reynolds told him "that she was going to remain NEUTRAL because I was, ‘Thank you President Trump,’ FIRST IN THE NATION."

"She wanted to campaign with everyone. I told her that I should have ‘remained neutral’ when she asked me to help her get elected, and that I didn’t want or need her to campaign with me," he said. "I am now 41+ Points up in Iowa!"

Former President Donald Trump

Former President Trump speaks to a crowd during a campaign rally on Sept.h 25, 2023, in Summerville, South Carolina. (Sean Rayford/Getty Images)

Trump went on to reflect on his past support of Reynolds, citing a Morning Consult poll, which says Renyolds is "America’s most unpopular governor."

"That’s because people don't like disloyalty!" he said. "I opened the position for Reynolds, so she became Governor of Iowa, by moving Terry Branstad to China as Ambassador. I then helped her when she was substantially down and losing to the Democrat Candidate, and worked hard to get her Elected, including an Endorsement and Big TRUMP Rallies.

"Very importantly, I was the sole reason that Iowa remained FIRST IN THE NATION," he said. "I was Strong on Ethanol, DeSantis voted against it, and other things bad for Iowa, like wanting to destroy Social Security and Medicare."

TRUMP WINDS MAJOR HOME-STATE ENDORSEMENT IN SNUB TO DESANTIS

"Despite all of this, Reynolds remained Neutral on Endorsements, and she is now America’s most Unpopular Governor, and Ron DeSanctimonious is Second," Trump continued. "That’s what happens when you are disloyal to those that got you there!"

Kim Reynolds

Iowa Gov. Kim Reynolds speaks during a campaign kickoff event for Florida Gov. Ron DeSantis in Clive, Iowa, on Tuesday, May 30, 2023. (Al Drago/Bloomberg via Getty Images)

Trump's comments come ahead of the expected endorsement Monday night. Reynolds, the popular two-term GOP governor of the state, is set to join DeSantis at his rally in Des Moines as a "special guest," according to a social media account associated with the Florida governor’s presidential campaign.

Iowa plays a crucial role in the race for the White House, as its caucuses for half a century have kicked off the GOP presidential nominating calendar. Additionally, Reynolds faced criticism from Trump earlier this year for her pledge to stay neutral in the presidential nomination race, which is in line with previous Iowa governors. 

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While she remained neutral in the 2024 GOP nomination battle as the field of contenders grew to over a dozen candidates, Reynolds – who convincingly won re-election to a second term last year – had repeatedly not ruled out endorsing as the Jan. 15 Iowa caucuses neared.

DeSantis has concentrated the vast majority of his campaign trail time and resources in Iowa the past couple of months and has so far made stops in 87 of the Hawkeye State's 99 counties.

Fox News' Paul Steinhauser contributed to this report.