This resolves to whichever of the four candidates above (the ones being tracked by 

) suspends their campaign for the GOP presidential nomination first, provided that it happens before June 8. If no one leaves by June 8 (the date of the last caucuses), resolves to that option.

Note: If the Supreme Court rules that Trump is ineligible to run, I'll count that as suspending his campaign. A ruling by a lower court wouldn't count, since it could be appealed. 

I would also count it as leaving the race if one of the candidates died.