So dumb. You don't need 50% of the vote to win the nomination, presumptive nominees just end up with >50% of the vote because once they clinch the nomination, most voters in the remaining states just end up voting for them. It's very likely the Republican nominee wins the nomination next year with <50% of the popular vote because there are less winner-take-all states and more proportional ones, so the primaries can make it all the way to June. Or not. Who knows?
McCain in 2008 only ever got up to 47% of the primary vote.