The sabotaging of Carter's re-election began the day he won the nomination. He was a wishy-washy politician with no political clout outside of his home state. He was a lousy president but, probably the closest thing to a decent human being we have seen in the office in over a century, which is not a very high bar.
I was too young to vote during his time in office only turning 18 the Summer of 1980. I do remember how he was viewed in my home area.
At the time Oklahoma was still a (old school) Democrat state. Mr. Peanut was NOT popular with the farmers and ranchers I knew and associated with.
I also had some association with union members (American Airline employees) that hated him and became staunch Reagan supporters during his campaign.
The blame for the flusterlcuck that was the attempted rescue mission of course falls to him as Commander In Chief but the reasons and causes were largely in my opinion the fault of the brass at the Pentagon. IIRC Carter wanted it to be a Navy operation but every branch just had to have a piece of the glory pie. The problems with inter-service communications and cooperation was a significant factor in the failure of the operation.
His domestic and foreign policies were also not popular and some parts of his legacy are still a problem to day, like the Department of energy.
He really didn't need outside help to insure his defeat, he was managing it pretty well on his own.