According to conservative pundit Quin Hillyer, former U.S. Senator Tom Coburn is open to challenging Trump:

“I can reliably report that the former U.S. Senator from Oklahoma, Dr. Tom Coburn, would accept a draft from the convention floor if delegates petition successfully to put his name in nomination.”

Reportedly, Coburn will not openly campaign for the nomination but would accept the nomination if nominated.

Finally, Coburn being willing to challenge Trump would alleviate the concerns of the Rules Committee about unbinding the delegates without having an alternative.

Either way folks, it’s gonna be a crazy convention, hold on to your hats.