I think that would have to be the POD. The attempt to free the hostages would also have to succeed for him to have any chance.He picks someone other than Paul Volcker as Fed Chair and/or Volcker pursues different monetary policies. While Volcker's policies did allow the economy to recover and grow in the long term, the negative effect it had on the American economy in the short term all but doomed Carter.
Is it plausible to have Carter NOT give the Shah refuge in America?