For John, BLUF: You have to have a path to the nomination. Nothing to see here; just move along.
From the Five-Thirty-Eight blog on "Leap Day" there following links talk to the path to nomination by the two five candidates (three Republicans and two Democrats). They do not talk to a "Brokered Convention", one in which no candidate has the necessary delegate count to cinch the nomination (1237 for a Republican and 2026 for a Democrat).♠
♠ Remember, WCAP notwithstanding, the Republicans have far fewer Super-delegates than the Democrats.