Any state voting before March 15 has to allocate delegates proportionally, so that you could see multiple candidates getting delegates. Thus Cruz, Trump, and Rubio walk away from the Iowa caucuses with almost exactly the same number of delegates. However, states that have primaries after March 15 can, at their choosing, make it winner take all, which means that whichever candidate gets the most votes wins all the state’s delegates – even if the candidate’s vote total is less than 30%. Except… many of those winner-take-all states allocate their delegates at the congressional district level, which means that different candidates can win in different congressional districts, thereby splitting up the vote. You probably didn’t pay attention to this last night, but there was a significant difference in preferences among various Iowa counties. The same thing will hold true in the congressional districts of winner-take-all states.
Further, Nancy Pelosi’s district is going to get three Republican delegates (which may be all the Republicans in her district). My own district is heavily Democratic – one of the joys of living in downtown Dallas. This will be my first presidential voting season since I moved here, and sadly I have no idea how my fellow local Republican voters feel about this election. When I say I haven’t been involved since 2000, that is really true. And since moving to Dallas County from Tarrant County, I have had very little contact with local politicians other than a few congressmen who have been around forever.
Now here is the interesting part. How delegates are selected is really controlled by the individual states. In some states the delegates are chosen by the winning presidential nominee. In other states the nominee can make a suggestion, but the congressional district is not bound to follow it; the district just has to send delegates who pledge to vote appropriately for the required number of roll-call votes. I am sure there are many variations on the above.
Let’s take that concept to Texas. You could get the odd situation where a pledged Trump delegate is actually a Cruz supporter and goes to the convention. Trump would get his or her first vote. Or, you could get a delegate pledged to Cruz from a congressional district where the majority actually prefers Trump. Same with Rubio or Kasich or Carson or Rand Paul. I’m not certain whether things have changed, but when I was involved, Ron Paul had a much larger percentage of supporters among party participants than he had votes.
What I’m saying is that, if a majority of delegates at the national convention don’t vote decisively for one presidential candidate in the first round, it is really not clear what will happen in the second or third rounds. At that point, delegates are free to vote their conscience and convictions.
Now let's throw a wrench into the gears, in the form of an odd rule. Since 1972 (I think it was), a candidate could get his or her name placed in nomination at the convention by winning a plurality in five states. That rule was put into place to keep states from running “favorite sons” who could claim the full right to long nominating and seconding speeches and then their personal speeches as well. Conventions could get rather long-winded in the old days, as future presidential nominees liked to get their names and faces in front of the nation. So a structure was put into place that worked perfectly well for 40 years.
That is, until the last election cycle, when the Romney campaign engineered a rules committee change which said that the nominee had to win a majority of the delegates in eight states instead of a plurality in five, which basically meant that Ron Paul would have no chance to have his name placed in nomination at the upcoming convention. That is the way the rule still stands today (with a few cosmetic changes). No one back then had any idea that the current primary process would be so open. Further, given the scattered nature of the process, it is perfectly plausible that only one candidate will actually get a majority in eight states, but without getting a majority of the overall delegate count. (You can read all the rules here.)
But – and this is a huge but – the rules as they are written now are not the rules the convention will have to follow. Each convention adopts its own rules. Each state will appoint a member to the rules committee, which will meet prior to the convention to put together the new rules under which the convention will be convened. Those rules will be presented to the convention in toto – there can be no amendments offered from the floor. An amendment can be tendered only if 25% of the rules committee members want to propose an alternative rule. It’s possible, but it doesn’t happen very often.
Now here’s the fun part. Let’s say one candidate gets 40% of the delegates and most of the remaining 60% are split between two major candidates, plus a smattering here and there. If the delegates representing the 60% don’t want to adopt the current rule requiring a candidate to win a majority in eight states, they can reject the rules (in toto), and force the rules committee to go back into emergency session and keep coming up with new rules until they get something a majority of the delegates like. Which could be rules that allow more than a few names to be placed in nomination, which would then open up later roll-call votes.
Further, the delegates for a candidate pledge to vote for that candidate on the first roll-call vote – but not necessarily to vote his way on any rules committee vote. So here again, just theoretically, that Trump delegate who is actually a closet Cruz or Rubio (or Christie or Paul or Kasich or whoever your favorite guy is out of the horde) supporter could vote to reject the rules until the process was opened up to more nominees.