To win The Contesting, he’d have to persuade over 25% off Trump’s delegates to change their vote.
I don’t see how he’s going to persuade that many people who made the trip with full intention of voting Trump into nomination.
I also think that Cruz has very little chance to get away with it, but we have to remember in places like Arizona, where Trump received over twice as many votes as Cruz, all of the delegates are purported to be Cruz operatives. A delegate is suppose to represent the interests of the voters, but the Cruz campaign has been working hard to subvert this process. They say it is all good because they are “following the rules”.