What complicates the picture is the GOP’s rule requiring the 28 jurisdictions (states, territories and the District of Columbia) that vote before March 15 to award their delegates proportionally. The exception is South Carolina, whose winner-take-all primary was grandfathered in. Add in the eight states voting on or after March 15 that also award their delegates proportionally, and some 60% of the convention’s likely total of 2,470 will be allotted that way.

Of these delegates awarded on a proportional basis, some states require a candidate to hit a floor—say, 20% or 15% of the vote. Others have lower thresholds or none at all. For example, Iowa’s 30 delegates will be divvied up proportionately with no minimum, meaning candidates win a delegate for each 3.3% of the vote they receive. The upshot is that by mid-March the top three or four candidates may be separated by only a small number of delegates, giving the leader a plurality, not a majority…

Still, with only around 40% of the delegates chosen in winner-take-all contests, they may be splintered enough that no candidate commands an outright majority. A complicating factor is that roughly 8% of the delegates will arrive at the convention unbound, free to vote for their choice of candidate. The delegates from Wyoming (29), North Dakota (28) and Guam (9) will be officially uncommitted, as will all but 14 of Pennsylvania’s 71 delegates.

Moreover, GOP rules allow for the creation of “superdelegates,” with more than half of state parties exercising the option to make their chairman, national committeewoman and national committeeman automatic delegates. These uncommitted delegates, 210 in all, could be the most fluid force in the convention if no candidate has locked in victory.