Carter ran against Ford who beat Regan in the Primaries.At least that’s how I thought it was.
The OP said angry about Reagan as some sort of excuse to vote for Carter or for Carter’s win . Maybe, but I thought really it was more about not liking Ford because of his association to Nixon. But yes Reagan lost the primary, so I guess maybe anger at that caused some to sit home. I can’t see Reagan supporters flipping to Carter out of spite. But I was in 1st grade at the time and can’t recall such details. 😂