It's Trump. All he has to do is tell everyone how beta the other GOP'ers were to his every whim. He can make them all come off as super weaklings that bend to the powers in Washington and don't have their own backbone. GOP in a tough spot unless 1. you like the trump stuff and/or 2. you were able to quietly not support trump and not make the radar over the last 4-5 years.
No body can beat trump, with the base, and maintain a strength and power image.