I have been writing about whether or not "Republicans" will go through with stealing the nomination from Trump at the convention even if he has the most delegates (here, for example). What I haven't been addressing is that Trump is, well, kind of a moron, and playing into the hands of the Stop Trump movement.
Here's the deal. The "Republicans" who make the formal decision about whom to nominate at the convention are not congressional leaders, interest group leaders, etc. They are people who can be influenced by those leaders, but the actual decision-makers are the delegates. The primaries and caucuses bind the delegates to vote a certain way on the first ballot at the convention, but after that, they are basically free to vote however they want.
And Trump hasn't been playing the delegate selection game. Cruz has been working to ensure that as many delegates as possible are Cruz loyalists so that if the convention goes to a second ballot, they vote for him. Trump hasn't bothered, expecting to win on the first ballot.
Trump, of course, is whining about it, because Trump is a whiny, little Donald.
Currently, he is claiming that the nomination game is rigged. Is it fair? Fairness doesn't exist (see my comments here). For Trump to complain about losing through the delegate selection game is like a novice poker player whining that the game is rigged because he lost a hand to an opponent who bluffed. That's the game. And Trump doesn't understand the game.
What does this mean for the convention itself? Cruz loyalists will have no qualms about screwing Trump out of the nomination. If Cruz can get enough loyalists on the delegate slates, he will win.
The problem is that there will be plenty of delegates who both hate Cruz, and won't want to deal with the chaos unleashed by screwing the delegate leader out of the nomination.
For what it's worth, the betting markets currently put Trump's chances at around 55%, and Cruz's at around 35%. Is that right? Who knows at this point?
Of course, there is a flip-side to this. Many people, myself included, thought that Trump would never go through with a formal campaign. I thought it was all just a publicity stunt, until he actually showed up for the first debate. The problem with going that far is that Trump is probably a weak general election candidate. So, either he would have to quit, or eventually lose. Trump hates losing, but if he can claim he got screwed, then he can lose with whatever the Trump analog of dignity might be.
Perhaps, then, he wants to get screwed out of the nomination at the convention because that would be less embarrassing than having his ass handed to him by Hillary,
With Trump, though, everything is speculation.