Should the GOP adopt a "no more Trumps" rule for 2020?

The first would be a more or less explicit “Trump Rule”: a candidate who does not meet a minimum threshold of experience within the party may not be awarded the majority of delegates in any state. “Extra” delegates won by votes for such candidates could be allocated to unbound “superdelegates.” A minimum could be four or six years in certain specified offices as a Republican – Governor, Senator, Representative, Vice President, Cabinet Secretary, Mayor, state Attorney General, perhaps a few others. Not an onerous requirement; if it’s four years, every past nominee but Eisenhower and Willkie would qualify, as would 14 of the 17 candidates in 2016 (all but Trump, Ben Carson and Carly Fiorina). A similar rule would have placed a ceiling on past candidates like Herman Cain, Pat Buchanan, Steve Forbes, and Pat Robertson. It’s not unreasonable for a party to require as a minimum condition for being the party’s leader that you have actually worked in the party for at least four years. And styling the rule as a cap on state delegates rather than a ban on ballot access or an absolute bar to the nomination would preserve the ability of Buchanan/Forbes style protest candidates to run message campaigns with which the prospective nominees must compete for votes. as well as preserving the possibility that an outsider with a truly broad popular majority mandate (someone like Ike) could be chosen at the convention if his or her presence in the race swamped all competitors and was seen by party insiders as acceptable and/or necessary.

The second potential rule change – which might be difficult to enforce in terms of ballot access, but could be effectively enforced through rules on delegates and debates, assuming the primary calendar is less compressed and less geographically unbalanced in the future – would be to have an escalating series of thresholds that a candidate must pass in order to remain in the race. Such thresholds already exist for debates, but they are very low and tend to rely on polls; these would be based on delegate and/or popular vote results in the early states. In years past, candidates staying on pointlessly after their own chances had evaporated was less of an issue, but SuperPAC financing, the opportunity to act as a stalking horse for another candidate (including a well-funded candidate who can wash away your campaign debt) and the chance for candidates to cash in (e.g., by selling books) by staying in too long is bad for a process that’s designed mainly to choose a single nominee. The most egregious example in 2016 was John Kasich, who through Super Tuesday had won just 6.6% of the popular vote and finished fifth or lower in nine out of fifteen primaries – yet Kasich remained in the race another two months without ever gaining major popular or financial support, winning only his home state but siphoning off votes from the real contest. Forcing a narrowing of the field puts the voters to a clearer binary choice as the race proceeds.