It was an agreement. The GOP is in breach of contract if they now try to torpedo their leading candidate. God knows. And so do we the people.
We already knew the establishment would try to take out conservatives its what they do, Trump knew when he signed it, or least he should have known, that is not disputed. What is disputed is how to maintain a presidential dignity, integrity and character when faced with adversity and dirty doubling dealing of the establishment. This is not some land deal in Manhattan, this is the highest office of the land and tone and character matter.
"I [name] affirm that if I do not win the 2016 Republican nomination for president of the United States I will endorse the 2016 Republican presidential nominee regardless of who it is. I further pledge that I will not seek to run as an independent or write-in candidate nor will I seek or accept the nomination for president of any other party."
At the first GOP presidential debate, Trump was the only guy who raised his hand when the group was asked, "Is there anybody here who wouldn't sign a loyalty pledge?"
Cruz was ABSENT from that first debate.
The agreement was Trump would support the final candidate and not go third party. I haven't read the wording of that agreement but doubt there was anything in there about them being "fair"or he could leave under that agreement.
I don't think the National Party can use their money to the detriment of Trump - try to make him lose. I say that because the Republican rule for a county chair is he/she can't show favoritism to any of their candidates. That has to be the rule for the National Party also.
There could be PACs not connected to the National Party and those could do whatever they want to try to destroy him. I don't see any way that could happen as Trump supporters are avid supporters.