Carter was renominated and Bush was/is not a worse President than him.
Carter was renominated despite being damaged because Ted Kennedy imploded after an embarrassing interview in which he failed to enunciate WHY he wanted to be President (aside from his grandiose sense of entitlement). His approval rating was also higher than Dubya’s, too. If Dubya tried to run for a 3rd term with approvals in the 20s or 30s, he would’ve been destroyed.