Political nerds had some fun with this scenario last night on Twitter so I wanted to pass it along. Remember Rule 40? If not, pause for a second and re-read this post from allllll the way back in January 2015 wondering what might happen if — gasp — the nomination came down to a brokered convention this year. Rule 40(b) of the RNC’s convention rules says that no candidate is eligible to be nominated unless he’s won a majority of delegates in at least eight different states. In a “normal” situation where the party is splintered, it’s no sweat that multiple candidates would satisfy that rule. For instance, if Trump dropped out tomorrow, Cruz would go on to win a bunch of states, Rubio would win a bunch, and Kasich might win a couple, potentially leaving no one with a majority of delegates but almost certainly leaving Cruz and Rubio with majorities in eight states each. Both of their names would be placed on the ballot at the convention, the first ballot would be deadlocked, and then we’d go from there. Easy peasy.

But that’s not how the splintering’s going in the world we live in. Right now it looks like Trump will win many, many states and Cruz and Rubio will be lucky to win more than a handful each. They might still be able to hold Trump under the 1,237 delegates he needs by doing that — but what if neither of them racks up majorities in eight different states? It’s not that far-fetched. Right now Trump’s won majorities in five different states while Cruz has won a majority only in Texas. Rubio hasn’t won a majority anywhere. What if Trump is the only candidate to meet Rule 40’s threshold? Jeff Berkowitz wondered about that and gamed it out in a piece yesterday at Medium:

Under this scenario, how many delegates Trump and other candidates have accrued, and how loyal they are to their candidate, will matter a lot. Why? Because if Trump secures a majority of delegates on that first ballot, he is the nominee. If he falls short of a majority, it goes to a second ballot, in which many delegates are no longer bound by the results of their state’s primary or caucus. In such a case, eight state delegations could agree to support another candidate and add that candidate’s name to the ballot. The rounds of balloting and politicking would continue until a candidate receives a majority of the votes.

Yet even before the first round of balloting begins, hijinks could ensue under this scenario. There are several opportunities to change Rule 40 before the convention begins the nomination process. The RNC will hold its spring meeting on April 20–22 and could modify the rules then. The rules committee will also meet on the eve of convention and could modify the rules then as well. Once the convention is underway, its first order of business will be to approve the rules, which affords delegates the opportunity to seek to amend them. And lastly, it may be considered in order for delegates to move to suspend the rules during the nomination process to allow Cruz, Rubio or another candidate who fell short of the Rule 40 threshold to be placed into consideration and receive votes on the floor from the delegates they won in primaries and caucuses.

The first ballot taken, and the only one in which delegates are bound by the vote of their state’s electorate, would list Trump as the only choice available. Assuming he made it to the convention without notching 1,237 delegates, he’d still be short of the majority he needs even running technically unopposed for the nomination. But Trump fans have an obvious argument there: Why should Trump need to win a majority of the delegates if he’s the only candidate who’s eligible for the nomination, at least during that ballot? If a congressman ran unopposed, he wouldn’t be denied his seat in Congress just because he didn’t win a clear majority of the registered voters in his district. Presumably the eight-state threshold for Rule 40 was picked by the RNC because they wanted the eventual nominee to demonstrate popular support among voters across a variety of different jurisdictions. Trump will have done that — and he’d be the only one who did. And if the response to that is “total delegates, not a majority in eight states, are the true indicator of breadth of support,” well, then why have Rule 40 in the first place? The correct answer is that the RNC was worried about a Ron-Paul-type insurgent challenging a Romney-type establishmentarian this year and figured that adding the eight-state requirement would create another obstacle to a floor fight mounted by an insurgent campaign. In reality it’s the insurgent Trump who’s benefiting from the Rule. Now the RNC’s stuck with it, even as it’s also stuck arguing that a total majority of delegates is all that matters.

But wait. Is the RNC stuck with it? David Byler foresaw the bickering over Rule 40 coming a few months ago and dismissed it as a nothingburger:

Republican lawyer Ben Ginsberg and University of Georgia political science lecturer Josh Putnam (who also runs the excellent FHQ blog) emphasized to RealClearPolitics that Rule 40(b) is temporary. In the week before the 2016 convention, the delegates will have multiple opportunities to change it, so no GOP presidential campaign has to worry about getting delegate majorities in at least eight states.

Right — but imagine the political backlash if the RNC tried to change Rule 40 now to hurt Trump and/or benefit Rubio. Imagine that Trump gets to the convention with a majority of delegates in 20 states and Rubio has a majority in just five, and suddenly the rule is changed to make five the cut-off for eligibility. Trump fans will scream that the establishment is rigging the game to help their fair-haired boy, and they’ll be right. Everything Trumpists have said about a corrupt political elite cheating the little guy to help their friends would be confirmed right there in Cleveland, in a national spotlight. Whatever small claim Rubio had to being the party’s legitimate nominee would be shattered.

The best case you can make for changing the rule anyway is, per Ross Douthat, that the party would already be irreparably shattered by the time we got to the convention regardless of what happens with Rule 40. If Trump ends up there with a near-majority of delegates and either Cruz or Rubio, with comparatively small minorities, ends up as the nominee as part of some deal, Trumpists are going to pronounce the system corrupt and failed and will walk away. On the other hand, if the #NeverTrump movement has any numbers behind it, nominating Trump will also cause a chunk of the party to walk away. The GOP splits regardless. Trumpists have declared war on the GOP and NeverTrumpers have declared war on Trump, and there’s no middle ground on that. In which case, who gets nominated is a pure matter of which brand the GOP wants to adopt in an all-but-certain losing effort in November. If they want to stick with conservatism, they might as well game the rules however they like to nominate Rubio and then wait for him to get 25 percent of the vote in the general election this fall. And if there’s now no way to avoid a brokered convention if the party plans on nominating anyone except Trump, then Rubio and Cruz might as well take Randy Barnett’s advice and declare today that they intend to support whichever of the two of them ends up with the most delegates at the convention. That at least will make the choice for Republican voters a bit starker. If undecided Republican voters want Trump, they can vote for him now. If they don’t, they should go on voting for Cruz and Rubio full in the knowledge that they’ll be getting one of them as nominee, even though it’ll remain unclear for the next several months precisely which one.

One other point. Byron York’s right that the more likely a brokered convention seems, the more important the identity of the actual delegates, who are typically selected at state conventions, becomes. That’s because, after the first ballot, they’ll be free to vote for whichever candidate they prefer. So for instance, all 50 of South Carolina’s delegates are required to vote Trump on the first ballot because he won the state a few weeks ago. But if Team Cruz shows up at the state convention and helps get dozens of pro-Cruz Republicans elected as delegates, he could effectively flip South Carolina on the second ballot. If 26 of the 50 switch from Trump to Cruz, voila — Cruz would now have a majority of the state in accordance with Rule 40. As if it wasn’t hard enough to thwart Trump, in other words, Rubio and Cruz now have to start thinking about how to intervene in various state conventions to try to maximize their support among the delegates chosen there. How hard could that be in, er, 50 states plus several territories?