Is there anything that Reagan’s 1980 primary opponents could have done to stop him?
If you want to keep Reagan out of the WH, I think the best thing to do is get him the GOP nomination in 1976. Fundamentals and issues on the ground were going to give Carter the edge no matter who he was facing. At that point, I don't think it's super likely that Reagan gets another chance in 1980. I think 1976 was a poisoned chalice election, so even in a worst-case where Reagan wins, we only get 4 years. And that actually might not have been so bad as it could have set up the 1980s as a decade of Democratic dominance.
