Only Wallace’s bid in 1968 really upended the popular vote. Even Ralph Nader’s bid in 2000 barely moved the needle because a number of his voters would have backed George W. Bush if Nader weren’t in the race.
Trump, on the other hand, could make a difference even if he experienced an Anderson-like slide to only 5 percent of the vote. If 70 percent of Trump’s vote comes from the Republican candidate (as it does in the ABC News/Post survey), we can estimate that the Democratic nominee’s chance of winning1 would rise from 50 percent (FiveThirtyEight’s default in a non-incumbent election) to 63 percent.
Of course, a Trump bid could earn more or less than 5 percent of the vote, and it could pull more or less support from either Democrats or Republicans than Trump is right now. So let’s look at different scenarios. Here’s a matrix that gives the Democratic candidate’s chance of winning at this point depending on varying levels of support for Trump.