We’ve all heard less about third-party options this year than we did in 2016, because there’s less demand for them on the right and the left. Conservatives who wondered whether Trump would be a reliable ally on issues such as taxes, abortion, and judges back then have had those doubts quelled; many have made their peace with what used to bother them about him. (The Libertarians that year also put up a ticket with more conventional qualifications than usual, and have reverted to form this year.) Liberals are often dissatisfied and complacent in the eighth year of a Democratic presidency, and then get shaken out of those attitudes by Republican presidents. Ralph Nader did a lot worse in 2004 than in 2000 for that reason.
The decline of third parties over the last four years, along with the decline in the number of undecided voters, should change how we look at some of the polling averages. Clinton’s margin over Trump in Wisconsin was bigger on this day in 2016 than Biden’s is now, as David Harsanyi has usefully reminded us. But Biden is at a higher level than Clinton was: He’s at 49.7, where she was at 45.7. (He’s also at a higher level than Clinton was in Arizona, Florida, Georgia, Michigan, North Carolina, and Pennsylvania.) Assuming — and this is of course a big assumption — that the current average is close to a true picture of voter sentiment, Biden need only keep those who are leaning toward him and convert a tiny sliver of undecideds to win an outright majority. That’s a much better position than Clinton was in.