‘The term “October surprise” was originally used by the Reagan camp to describe its fears that Mr. Carter would manipulate the hostage crisis to effect a release just before the election.

To forestall such a scenario, Mr. Casey was alleged to have met with representatives of Iran in July and August 1980 in Madrid leading to a deal supposedly finalized in Paris in October in which a future Reagan administration would ship arms to Tehran through Israel in exchange for the hostages being held until after the election.’

https://www.nytimes.com/2023/03/18/us/politics/jimmy-carter-...