Former president Jimmy Carter has maintained a cordial if cool relationship with fellow President Donald Trump, giving him occasional advice on China and even praying for him. Trump himself has been as friendly as might be expected, wishing him a “speedy recovery” from hip surgery one day and calling him the second worst president the next. But whatever comity existed likely ended Friday, when the 94-year-old Carter told an audience at the Carter Center that he did not believe Trump was legitimately elected.

“I think a full investigation 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 during a panel event on human rights, moderated by historian Jon Meacham.

“So do you believe that President Trump is an illegitimate president?” asked Meacham. Carter paused. “Basically, what I said, I can’t retract,” he responded, to the laughter of the audience. Meacham then went on to ask about Eleanor Roosevelt.

Prior to this, Carter had hedged his criticism of Trump, calling him “very careless with the truth” but adding that he is “not here to criticize the incumbent president.” The suggestion that Trump was not legitimately elected, however, is an emotional trip wire for the current West Wing resident, to the point that Trump has reportedly avoided the topic of preventing further election interference for fear that such discussions will taint his presidency.

Former vice president Walter Mondale, who was seated next to Carter, went further. “Doctors tell me that they think they recognize symptoms of psychological problems in him. You can almost predict now, what he’s going to do. It will be about him, he will celebrate him. He will be right and we will be wrong no matter what goes on. That’s what he does. There is some need for him to do that.”

“I think he just stole my headline,” Carter quipped.

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