In an apparent change of heart, former U.S. President has criticized politicians who refuse to say whether they have received COVID-19 booster shots, calling them "gutless.”

"You gotta say it. Whether you had it or not, say it,” Trump said in an interview that aired Tuesday night on the conservative One America News Network.

Trump, who was booed last month by supporters after revealing he had gotten a booster shot, has become increasingly vocal in calling out those who have questioned the vaccines’ efficacy and safety. It’s a change in posture for Trump as he eyes another run for the White House and faces potential competition from a long list of possible Republican challengers.

Even though the vaccines were developed during the Trump administration, they remain deeply unpopular with large segments of the Republican base, fueled in part by rampant disinformation. Trump, while in office, consistently downplayed the risk posed by COVID-19 and he received his vaccine privately, even as other members of his administration were inoculated in public to help boost confidence in the shots.

"Well, I’ve taken it. I’ve had the booster,” Trump said in the interview. "I watched a couple of politicians be interviewed and one of the questions was, ‘Did you get the booster?’ .... And they, ‘Oh, oh,’ they’re answering it – like in other words, the answer is ‘Yes,’ but they don’t want to say it. Because they’re gutless.”

Trump did not name names, and his spokespeople did not immediately respond to questions about which politicians he was referencing. But Florida Gov. Ron DeSantis, a rising star in the Republican Party who is often mentioned as a possible 2024 presidential contender, has notably declined to say whether he has received a booster.

"So I’ve done whatever I did, the normal shot. And, you know, that, at the end of the day, is people’s individual decisions about what they want to do,” DeSantis told Fox News Channel host Maria Bartiromo last month.

DeSantis’ office did not immediately respond to a request for comment Wednesday.

Many House Republicans, including top Trump allies, have also declined to disclose their vaccination status. Some such as Georgia Rep. Marjorie Taylor Greene are open about their refusal to get it.

By criticizing other politicians reluctant to disclose their vaccination status, Trump appears to be looking to turn the shots into a political issue that allows him to promote his administration’s success in facilitating their development while creating a contrast with other possible 2024 GOP candidates loath to upset the base.

In recent weeks, the highly contagious omicron variant has driven record case counts, overwhelmed hospitals and disrupted essential services because of staffing shortages. The booster has been shown to significantly bolster immune protection against the variant, and the Biden White House has urged Americans to take the shots.

In an interview last month, Trump seemed to acknowledge the risk many of his supporters were taking by not getting vaccinated, though he has repeatedly said he is against mandating the shots.

"This was going to ravage the country far beyond what it is right now. Take credit for it. Take credit for it. ... Don’t let them take it away. Don’t take it away from ourselves," he said in December during an appearance with former Fox News host Bill O’Reilly when Trump first revealed he had received the booster and was booed by some in the crowd.

In an interview with conservative commentator Candace Owens, Trump stressed how well the vaccines work at preventing hospitalization and serious illness.

"The ones that get very sick and go to the hospital are the ones that don't take their vaccine," he told her. "People aren't dying when they take their vaccine.”

Owens, a longtime Trump supporter, later sought to undermine Trump's support of the vaccines in the interview by pointing to his age, 75.

But in the OAN interview, Trump did not relent.

"The fact is that I think the vaccine has saved tens of millions of people throughout the world. I have had absolutely no side effects," he said. Still, he repeated his opinion that young people, for whom serious complications for the virus are rare, should not be vaccinated, even though health officials have urged everyone who is eligible to get the shots.

Trump was hospitalized with COVID-19 in October 2020, weeks before the presidential election, and received experimental monoclonal antibody treatment.