It was primarily the "Iran Hostage Crisis" that hurt Carter in the election of 1980, since this crises ended up getting dragged out for longer than expected and made the US look weak.
The Iran hostage crisis was the foreign policy issue hurt Carter in the election of 1980
Explanation
The Iranian hostage crisis took place back in the year 1979 when a group of people who were Iranian citizens stormed the US embassy taking Americans citizens and diplomats hostage.This happened after shah was allowed into the US after a long debate. Shah was a allowed for cancer treatment. This angered the Ayatollah and they attacked the Us embassy which was in Tehran Iran. The attackers were militants and college students who claimed to be Khomeini disciples.
