At this point in the election cycle, the average error of polls for all elections is just 3.3 percentage points (much lower than the 4.7-point error we found for just after the conventions), and
every candidate who’s been ahead in the popular vote in mid-October went on to win the election.
Simply put, there isn’t a precedent for a candidate coming back to win this late in the game after being behind by as much as Trump is now. That’s not to say Trump is dead in the water — polls are not perfectly predictive — but history doesn’t offer much hope for candidates in Trump’s position.
The nearest precedent available — if you squint and cover one eye — is probably 1992. The polling error that year, 8.5 percentage points, was larger than Trump’s current deficit in our polls-only forecast. In mid-October of 1992, Bill Clinton held a double-digit lead over George H.W. Bush. Clinton won, but only by about 6 points.
But the 1992 campaign isn’t a great model for the Trump campaign. First, Bush still lost. Second, 1992 featured a strong independent candidate in Ross Perot, which made
polling the race more difficult. Gary Johnson’s support, in contrast, appears to be shrinking, which creates less volatility. And while Bush was hemorrhaging Republican support — as
Trump is now— he still
ended up losing more Republicans than Bill Clinton did Democrats on Election Day. That won’t work for Trump this year given that there are usually
more self-identified Democrats than Republicans.
Trump’s supporters are better off pointing to two other races, 1980 and 1968, though neither of those are particularly encouraging either. In 1980, Ronald Reagan had a small lead over Jimmy Carter at this point in the campaign but ended up crushing Carter by nearly 10 percentage points. So that’s a decent precedent for Trump, right? Not really. The 1980 race shifted a great deal in the final weeks of the campaign, but even if 2016 underwent a similarly sized lurch towards Trump, he’d still lose. Not only that, but Reagan still had a major card to play in that election: the
only debate between him and Carter. Reagan’s
calm, collected performance there gave him a significant boost in the polls. This year, of course, two debates are already in the books, and Trump has
lost both. Trump could obviously do better in the third debate, but it would likely have far less of an impact than the lone Carter-Reagan debate in 1980 did.