Carter made the comments during a discussion on human rights at a resort in Leesburg, Virginia, without offering any evidence for his statements.
“There is no doubt that the Russians did interfere in the election,” Carter said.
“And I think the interference, though 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.”
The U.S. intelligence community asserted in a 2017 report that Russia had worked to help Trump during the election and to undermine the candidacy of Democratic opponent Hillary Clinton.
WATCH: George W. Bush shakes hands with Trump, former presidents
But the intelligence agencies did not assess whether that interference had affected the election or contributed to Trump’s victory, and no evidence has emerged that votes were changed improperly.
Deanna Congileo, a spokeswoman for the Atlanta-based Carter Center, declined a request Friday to speak to Carter for further explanation.
Special counsel Robert Mueller’s report identified two criminal schemes by Russia to interfere in the election: the hacking of Democratic email accounts and a social media campaign to spread disinformation online and sway public opinion.
But Mueller’s report did not establish that Russia conspired with any Trump associates in those efforts.
Carter’s comments came during a panel discussion at a retreat for donors to the Carter Center, an organization he founded in 1982 that has been at the forefront of election monitoring efforts around the globe for decades.
The discussion was broadcast byCSPAN.
Panel moderator and historian Jon Meacham asked Carter if he believed Trump was “an illegitimate president.”
Carter replied: “Based on what I just said, which I can’t retract, I’d say yes.”