Between 2016 and 2020, the nonmajor party share of the presidential vote dropped from 5.7 percent to 1.9 percent. It's impossible to determine whether that factor had a decisive impact on the fact that Donald Trump won the former race and lost the latter; after all, he lost the popular vote in both elections. But if you accept the proposition that his conduct and character have placed something of a cap on his popularity, the availability of robust minor-party or independent candidacies to divert anti-Trump votes seems significant.
