Complex sentence: Its failure, and the humiliating public debacle that ensued, damaged American prestige worldwide and is believed by many, including Carter himself, to have played a major role in his defeat in the 1980 U.S. presidential election.
Split into simpler sentences: Its failure, and the humiliating public debacle that ensued, damaged American prestige worldwide. Many believe that this failure played a major role in Carter's defeat in the 1980 U.S. presidential election.