The rules are ALREADY in place to do this, “winner take all”. Unlike the Democrats, who proportion delegates by vote, almost all Republican states award all delegates to the winner.
This means that the establishment candidate “automatically” gets all the delegates in huge left-wing states like California and New York, states Republicans don’t have a chance of winning in November. That huge sweep of delegates is almost impossible to overcome.
To give a real life example, under Democratic rules Mitt Romney would have been AHEAD of McCain in delegates on the day in which, in real life under Republican rules, Romney dropped out of the race because he was so far BEHIND in delegates!