Last time I looked at the caucus thread, Trump had five times the votes Cruz did.
That’s not a split: that’s a splinter group.
Trump does not have the full support of the base. Without it, he does not win. Period.
Just ask President Romney
http://www.nationalreview.com/corner/333083/romneys-base-did-not-turn-out-maggie-gallagher
Gratuitous assertions can be just as gratuitously denied. That's the rule in logic.
Furthermore, Trump's crossover appeal is undeniable. The only argument that can be made is "will it be enough," and there really isn't any data to evaluate that question yet.
Trump CAN win without "the full support of the base;" all he needs is votes.