Fagen noted that the delegates at the Republican National Convention are made up of the establishment's base, so they may not side with Trump in a brokered convention.
There is an argument to be made that if Trump does not secure the required delegates going into the convention, he is on equal footing with all other candidates, regardless of his technical lead in the delegate count, said Rick Tyler, former senior communications advisor for the Cruz campaign.
"Remember, a lot of the delegates who are elected … to go to the convention, most of these people have known the party rules for long time. They live to go to the convention. They have run to go to the convention. They may or may not be Donald Trump supporters," he told "Squawk Box."
To be sure, many people will be upset if Trump maintains his lead but is not nominated, Tyler said. It remains an open question whether Trump supporters will vote against the GOP, sit out the election, or settle on the party's alternative, he added.
Cruz asked for Tyler's resignation last month after the former aide admitted to promoting an inaccurate story about Rubio on social media.