Former President Donald Trump has lashed out at fellow Republican presidential candidate Vivek Ramaswamy ahead of Monday’s Iowa caucuses.

“Vivek started his campaign as a great supporter, ‘the best President in generations,’ etc.,” Trump wrote in a Saturday Truth Social post, referring to the biotech mogul’s past praise of the former president.

“Unfortunately, now all he does is disguise his support in the form of deceitful campaign tricks. Very sly, but a vote for Vivek is a vote for the ‘other side’ — don’t get duped by this.”

“Vote for ‘TRUMP,’ don’t waste your vote! Vivek is not MAGA,” he added.

Earlier that day, a senior Trump campaign adviser, Chris LaCivita, had attacked Ramaswamy on social media as a “fraud” in response to a photo of the candidate with supporters wearing T-shirts bearing the message, “Save Trump, vote Vivek,” along with a picture of Trump’s mug shot.

Trump aide Jason Miller told the New York Post it was “pretty safe to say” Trump won’t be choosing Ramaswamy as his running mate.

On Sunday, Ramaswamy responded to Trump’s post, calling it “an unfortunate move by his campaign advisors.”

“I don’t think friendly fire is helpful. Donald Trump was the greatest President of the 21st century, and I’m not going to criticize him in response to this late attack,” he wrote in a lengthy post.

It apparently did nothing to mollify Trump. In an all-caps screed Monday morning, he said: “A VOTE FOR VIVEK IS A WASTED VOTE. I LIKE VIVEK, BUT HE PLAYED IT TOO ‘CUTE’ WITH US.”

In a final Iowa poll by NBC News/Des Moines Register/Mediacom of likely Republican caucus-goers, Trump led with a commanding 48% support, followed by Nikki Haley at 20%, Florida Gov. Ron DeSantis at 16% and Ramaswamy at 8%.

Trump has previously spoken positively about Ramaswamy. Back in August, he called the upstart candidate a “smart guy” with “a lot of talent.”

“Anybody that said I’m the best president in a generation ... I have to like a guy like that,” he said at the time, when asked about Ramaswamy as a potential vice president.

Ramaswamy has styled himself after Trump and heaped praise on the ex-president throughout the race, pledging to pardon the quadruply-indicted front-runner if he makes it to the White House.

He saw a surge in popularity earlier in his campaign, but has since lost traction. Due to low polling numbers, Ramaswamy did not qualify for the most recent GOP presidential debate on CNN.