With just three months till the Iowa Caucuses, experts cite the real possibility that the GOP convention in Cleveland won’t be decided on the first ballot, creating a fluid, unpredictable situation.

Most of the delegates—60 percent—will be selected proportionally; only 40 percent will be awarded on a winner-take-all basis. That means that even if one candidate captures 75 percent of the winner-take-all delegates—unlikely in such a complex, competitive race—he’d still need a full third of proportional delegates to reach a majority. If five or more candidates stay in the race, that could be tough.

With no majority choice on the first ballot, the delegates would go to a second ballot or beyond, until consensus emerges. The prospect of a dark horse, who wasn’t damaged in bruising primary battles, becomes an appealing possibility.

And who’s the most likely “dark horse” choice? Speaker Paul D. Ryan, with his rash of positive publicity as a party-unifying pragmatist who remains devoted to solid conservative principles.