The former president also said he's not sure yet who he'll vote for in 2020 but wants a candidate capable of beating Trump

Former president Jimmy Carter, a regular critic Donald Trump, is reportedly making it crystal clear that he does not want Trump sticking around in the Oval Office for another four years.

At an event on Tuesday, Carter that he’s still unsure as to which Democrat he’ll be voting for come the next election but he believes it’d be a “disaster” for Trump to serve another term, according CNN.

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“I’m going to keep an open mind. One of the major factors I will have in my mind is who can beat Trump,” Carter said at a town hall at the Carter Center in Atlanta. “I think it will be a disaster to have four more years of Trump.”

Carter also said he voted for Sen. Bernie Sanders over Hillary Clinton in the 2016 Democratic primary, but had some reservesations this time around about the ages of the candidates. (Sanders is 78 while frontrunner Joe Biden is 76.)

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“I hope there is an age limit [to the presidency]. You know, if I were just 80 years old, if I were 15 years younger, I don’t believe I could undertake the duties that I experienced when I was President,” said Carter, who will turn 95 on Oct. 1.

He was 52 when he was elected to the presidency in 1976.

Age has been a hot topic leading up to the 2020 election, as the top three contenders for the Democratic nomination are all in their 70s Sen. Elizabeth Warren, at 70, is a few years younger than Biden and Sanders.

Though Carter didn’t mention any of the candidates by name, Trump took his comments as a dig at Biden, telling reporters, “He said that it was because Biden’s having a hard time, there’s no question about it,” according to USA Today.

Image zoom Former President Jimmy Carter Scott Cunningham/Getty

Relations between Trump, 73, and Carter have sometimes been cordial, with the two even sharing a phone call in June about the United States’ relationship with China. But Carter has been sharply critical of Trump as well, going so far as to question the validity of his presidency given Russia’s election interference in 2016.

According to the Atlanta Journal-Constitution, Carter said this summer that Trump called him to thank him for a letter Carter had sent him on the topic and to tell him “on a private line that the Chinese were getting way ahead of the United States in many ways.”

Carter also told The New York Times in 2017 that he’d be willing to team up with Trump on a North Korea trip to visit with Kim Jong Un and said he thought Trump had a tough go of it in the media.

“I think the media have been harder on Trump than any other president certainly that I’ve known about,” he told the Times. “I think they feel free to claim that Trump is mentally deranged and everything else without hesitation.”

Image zoom President Donald Trump Carolyn Kaster/AP/Shutterstock

Carter has, however, criticized Trump, too, telling CNN in 2018 that Trump’s decision to pull the U.S. out of the Iran nuclear deal was possibly the “worst mistake” Trump had so far made in his presidency.

Then in June, Carter said he believed there was “no doubt” that Russia had meddled in the 2016 election and that Trump’s victory was therefore illegitimate.

“There’s no doubt that the Russians did interfere in the election. And I think the interference, although not yet quantified, if fully investigated would show that Trump didn’t actually win the election in 2016. He lost the election and he was put into office because the Russians interfered on his behalf,” he said at a Carter Center retreat in Virginia, according to CNN.

After being asked if he thought Trump was an illegitimate president, Carter responded, “Based on what I just said, which I can’t retract.”