Washington (CNN) Former President Jimmy Carter suggested Friday that a full investigation into Russian interference in the 2016 election would show that Donald Trump didn't win the presidency.

"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," Carter said at the Carter Center's retreat in Leesburg, Virginia.

Asked if he believes Trump is an illegitimate president, Carter paused for a moment.

"Based on what I just said, which I can't retract," Carter said to audience laughter.

Special counsel Robert Mueller's report found that Russia waged a "sweeping and systematic" influence campaign during the 2016 election with the goal of electing Trump, but did not establish a conspiracy between Trump's campaign and Moscow.