It’s rare that President Obama and Reince Priebus, the Republican National Committee chairman, agree. In recent weeks, they both have said that the presidential nominating process is not rigged. They are right. But that hasn’t stopped those displeased with the results — not only establishment Republicans but also Democrats who support Senator Bernie Sanders — from insisting on changing the rules for the next election. Some tweaks are always in order, but both sides are trying to craft procedures that would have benefited them this time. As with generals fighting the last war, experience shows this rarely works and often backfires. “Every time someone tries to game out this system,” said Benjamin Ginsberg, a leading Republican election lawyer, “the great law of unintended consequences rears its head.”
For the 2016 elections, Republicans wanted to compress the initial primaries and limit debates so that an establishment favorite — Jeb Bush, for most — could wrap up the nomination early. Concurrently, conservatives insisted on the early Southern contests to better ensure victory for an ideologically suitable candidate.
The result was that the debates and calendar helped nominate the most nonconservative candidate in ages: Donald J. Trump.
Democrats changed the rules after their 1968 debacle to take control away from party bosses. That helped George McGovern win the 1972 nomination — he then lost in a landslide to Richard Nixon — and in 1976, paved the way for Jimmy Carter, the former governor of Georgia, not a favorite of the reform crowd.