In a continuing effort to show that 2020 is not just another 2016, I wrote about minor-party candidates at New York:

To put it mildly, the 2020 presidential contest is being haunted by what happened in 2016. For one thing, it helps explain the widespread belief that Donald Trump will win despite considerable evidence inimical to his cause, whether that belief is based on mistrust of polls, or observation of the enthusiasm of his base, or the suspicion that he sold his soul to the Infernal Lord Satan in exchange for earthly power.

There is one particular element of the 2016 experience, however, that may be less compelling than others looking ahead to November: the strength of minor political parties, which had a boffo year last time around. As I noted recently, there are multiple reasons for expecting a considerably diminished showing by the Greens, the Libertarians, and other minor parties in November, ranging from less-well-known presidential candidates to the impact of the coronavirus on ballot access in states where numerous petitions must be gathered. Justin Amash’s recently announced Libertarian candidacy could boost that party’s vote a bit, particularly in his home state of Michigan. But as Kyle Kondik and J. Miles Coleman argue in a new analysis at Larry Sabato’s Crystal Ball, there’s another big reason we can expect minor-party voting to decline: The major parties are significantly more united than they were in 2016:

“[T]he top election on this list [of strong third-party performances]— 1912 — is the cleanest example of a divided party leading to the rise of a big third party vote. Theodore Roosevelt, upset with the performance of his Republican successor, William Howard Taft, tried to win the GOP nomination. He was rebuffed, so he created his own party and ran for president. The Republican vote splintered, and Democrat Woodrow Wilson won the presidency easily despite getting only 42% of the vote.

“But we can also see this phenomenon in some of these other elections.

“George Wallace, the conservative, segregationist Democrat who ran third party in 1968, ran strongest in the South, the conservative region that had once formed the backbone of the Democratic Party but was in the midst of breaking away from its ancestral party over the party’s leftward evolution on civil rights and other issues.”

The biggest third-party showings preceded major-party splits or transitions, including Wallace’s (four years later the once-solid Democratic South had become solidly Republican in voting to reelect Richard Nixon). And there was quite a bit of noisy intraparty opposition to both Donald Trump and Hillary Clinton four years ago. In the current race, that has mostly subsided:

“This naturally removes some of the oxygen for third party candidates, and the lack of major intraparty strife makes this election, to us, more reminiscent of 2004 and 2012, when George W. Bush and Barack Obama won second terms in competitive elections that featured very low levels of third party voting. Indeed, in 2012, Florida was the only state were neither major party candidate took a majority of the vote — by 2016, there were 14 states where both major candidates polled under 50%.”

There’s another factor that may strengthen party unity while discouraging “protest votes.” Just about everyone expects a close election, and those who thought Clinton had it in the bag in 2016 and voted third-party (or stayed home) may be particularly immune to minor-party siren songs. The above-mentioned Democrats who are still shocked by what happened four years ago may put on the party harness and never even consider taking it off:

“This time, even though Trump generally trails nationally and in at least some of the most important swing states, he still is favored by betting markets, and he usually does better in polls asking people who they believe will win as opposed to those that ask who voters are supporting. Democrats, burned by expectations in 2016, likely will remain guarded no matter what the polls say.”

There’s a lot of uncertainty going into this election, much of it associated with how little we know about the trajectory of the coronavirus, the economic damage it has wrought, and how COVID-19 will affect voter turnout. But the odds are higher than ever that any “swing” vote late in the game will be oscillating between the Donkey and Elephant brands.