Rules and credentials could prove extremely important at the Republican National Convention if no candidate has acquired the necessary 1,237 delegates -- and possibly even if one does.
Yet you shouldn't believe the hype about Rule 40(b) -- that the fight over this rule will wind up determining the nomination, or at least forcing a choice between only two candidates. In fact, it's unlikely to make any difference.
The rule is designed to ensure a smoothly running convention by limiting the number of candidates who can be formally nominated. It was strengthened in 2012 to prevent Ron Paul from getting a formal nomination. As Josh Putnam explained, instead of needing a plurality of the delegates in five states, Republicans in 2012 required a majority of delegates in eight states, a much tougher hurdle. Either way, however, this rule would prevent John Kasich (who as of now has only won a single state) or any other candidate from being formally nominated before the first ballot.
In other words, the rule would appear to limit the convention to a contest between Donald Trump and Ted Cruz, who both will have met that standard.
But that's not how the rules work in practice.
First, delegates can vote for a candidate who does not qualify and has not been nominated. In fact, some delegates will be bound to vote for a candidate who does not qualify. The convention, if it follows precedents, will allow -- but not officially tabulate -- those votes. The number needed to win is still a majority of the total number of delegates -- 1,237 votes is the threshold in 2016. So narrowing the official choices down to two candidates does not ensure that someone will win on the first ballot.
In other words, we could get a first ballot that looks like this: Trump 1,150, Cruz 1,000, John Kasich 180, Marco Rubio 100, along with a smattering of other candidates. The official tally would only include Trump and Cruz -- and since neither would have hit 1,237, at least one more ballot would be required.
On subsequent ballots, new candidates can qualify for official nomination if they can provide evidence that they've cleared the eight-state standard. Unless the rule changes, it wouldn't bar a third (or fourth, or fifth) candidate from being nominated -- as long as he or she can demonstrate sufficient support.
So any candidate who actually has the votes will be able to win under the 2012 version of Rule 40(b).
It's very likely that delegates for Trump and Cruz will make up the majority of the Rules Committee and, at least initially, of the convention. So they could strengthen Rule 40(b), and attempt to prevent any newly qualified candidate from being nominated on a later ballot.
I'm skeptical, however, that any such rule would hold in practice. If the convention truly deadlocks -- if neither Trump nor Cruz can reach 1,237 -- and the delegates decide to turn to a new candidate, then I'm confident that they would simply do so, rules or not.
It's possible to imagine some rules changes that could matter a lot -- for example, if delegates bound to vote for a candidate on the first ballot were instead freed to vote any way they want. But the rule about which candidates are officially nominated just doesn't seem likely to make any difference.
Jonathan Bernstein, a Bloomberg View columnist, covers U.S. politics.