Appearing as a panel member on Tuesday's CNN Tonight, CNN presidential historian Douglas Brinkley repeated as if were fact the claim that Ronald Reagan's campaign in 1980 pressed the Iranian government to delay the release of the Americans held hostage to hurt President Jimmy Carter's reelection chances.

Neither host Don Lemon nor fellow CNN presidential historian Timothy Naftali noted that a Democratic Congress failed to find evidence of such illicit activity when they investigated the October Surprise conspiracy theory in the early 1990s.

At about 10:42 p.m. ET, during a discussion of President-elect Donald Trump's public questioning of reported intelligence on Russia hacking the DNC, author John Farrell asserted that in 1968 President Lyndon Johnson had reason to believe then-presidential candidate Richard Nixon had tried to derail peace talks with North Vietnam.

Farrell -- author of Richard Nixon: The Life -- seemed to wonder if Trump had some sort of illicit knowledge of Russian hacking as he compared the 1968 campaign to that of 2016:

There's an interesting parallel in that President Obama and President Lyndon Johnson in 1968 had the same sort of dilemma, in which case they had information -- perhaps incomplete information -- about the candidate that was running against the candidate who they hoped would be their successor, and they had to decide how to use it in the volatile last weeks -- in Johnson's case, in the last days of the campaign.

He added:

In Johnson's case, he decided that he couldn't use it even though he had advisors who urged him that he should because they didn't know that Nixon was personally involved. So we don't know exactly what Obama knows about Donald Trump's knowledge of the Russian hacking, but it's quite possible he faced the same kind of decision that Johnson did and made the decision for the same reason to let the election go ahead.

It was then that Brinkley jumped in to insert the October Surprise conspiracy theory into the conversation:

One point: 1980, Ronald Reagan was taking on Jimmy Carter, and there was the October Surprise meeting keeping the hostages in Iran. William Casey, people in the Reagan administration were interfering with foreign policy then saying, "Keep the hostages in until after the election." So it has happened before. It's not just Nixon here or Donald Trump.

Last February, Brinkley dubiously claimed that President Reagan "fabricated" a story that he had visited one of the Nazi death camps at the end of World War II.

Naftali then added:

LBJ did use the material, though. with Nixon. He told Nixon he knew what he had done, and he used that to push Nixon to talk to the South Vietnamese to get them back to the table after Nixon had been elected.

Lemon made a joke about how much he could remember from the past as he responded: "I'm realizing how old I am. I don't remember the LBJ stuff. I definitely remember the Reagan stuff."