>> huge shift to the GOP for other candidates
I don’t think there was much of a shift. If you saw exit polls showing otherwise, let me know.
Both sides brought people who did not vote last time.
Maybe the switch, or abstained, voters are those that are the difference between other GOP candidates and Trump, and they made a big difference. Some argue that Trump’s policies and achievements without his personality would have more votes, but it is not clear whether many voters would show up without his personality. Mitt had a pleasant personality but it did not get him enough votes.