It's hard to tell. In the 2016 primaries Trump had 44% of the vote. That's a lot, and it's more than the other candidates, but its not a majority of the total vote. In the earlier primaries he most of his victories were in the 30's. So now you have to guess where he ranked for the 60-70% of people that voted for other people in early primaries. He might have still won, or other candidates could have emerged with majorities.
https://en.wikipedia.org/wiki/Results_of_the_2016_Republican...
[edit] I guess that doesn't really answer your question, because you asked about this election...
[edit] I guess that doesn't really answer your question, because you asked about this election...