God loves a runoff my man.
wish we had them here in Davy Crockett land
More opposition helps Graham. He is already pretty assured to be the top vote getter in the primary, but probably not 50%. He can sit on most of his money and watch his challengers go at it, spending what little money they have for the campaign. If there is a run-off, he will have about 50 times the cash as his opponent, allowing him to dominate the TV and radio.
Another possibility is the opponents beat up on each other to a point they look weak, Graham pumps in big money the last two weeks before the primary Election Day and captures more than 50% of the vote.
Either way, with a large field, I see no way Graham is defeated next year by a republican.