Monmouth University is the most recent to show a big swing in Hillary Clinton's favor. Its just-released national survey has her leading Trump by 12 points, 50-38. That 12-point margin is the biggest so far this month. A new NBC-Wall Street Journal poll over the weekend also had Clinton ahead by double digits — 11 points — and other recent high-quality polls have shown her up 9 points (NBC-WSJ last week), 8 points (George Washington University), 7 points (Fox News) and 4 points (Washington Post-ABC News).
According to HuffPost Pollster, Clinton's average lead in these high-quality polls is now 8.9 points.
At this point in the cycle, no candidate who has seen such big deficits in any poll — much less the average of all polls — has recovered to win. The only poll of the six mentioned above that is even within the margin is the Post-ABC poll.
Now, to the caveats:
First off, there are lots of polls today, but that wasn't always the case. Before the turn of the century, we're largely talking about only Gallup polls, and even those were infrequent the further back you go. If there were more polls conducted way back when, perhaps we would have seen a late double-digit deficit or two overcome.
Secondly, we're only talking about 20 elections for which we have Gallup data, from 1936 to 2012. So the fact that a comeback this big hasn't occurred over that span doesn't mean it's impossible — just that it hasn't happened in 20 elections.
And third, we have seen big late swings, but they were generally a candidate who trailed by a modest amount going on to win by a comfortable margin — not a candidate who trailed big coming back to win.
But the point stands that Trump would be doing something basically unprecedented. Below, we break down the three most recent examples of candidates overcoming late deficits to win the presidency.
2000 — George W. Bush
A couple of isolated polls in mid-September and early October showed Bush trailing Al Gore by 14 points (Newsweek) and 11 points (Gallup), respectively. But those were basically the only polls that showed such a lopsided race.
And the Gallup poll was clearly a blip. While the poll showing Gore up 51-40 was conducted Oct. 2 through Oct. 4, Gallup's own poll just days prior — from Sept. 29 to Oct. 1 — had a 45-45 tie, and its poll conducted immediately after the 11-point Gore lead showed Bush actually taking a significant lead, 48-41 — between Oct. 4 and Oct. 6.
The blip is clearly evident on the chart below, and by this point in the cycle, Bush had asserted a lead in most polls.
Similarly, Newsweek's Sept. 14-15, 2000, poll had Gore up 52-38 — a striking margin. At that same point, Gallup showed Gore up a more modest 6-8 points. And by Sept. 20-22, Newsweek's own polling showed Gore's lead had declined to 2 points. So another apparent blip that wasn't really substantiated by other polling — or, at the very least, was not sustained.
It bears noting that both of these polls showing Bush down double digits came earlier in the cycle than the new poll. Gallup's 11-point deficit came in a poll that was conducted more than a full month before Election Day. The newest polls today are less than four weeks out.
(And yes — Bush did actually lose the popular vote nationally, with a path to a presidential win that was, shall we say, atypical.)
1980 — Ronald Reagan
This is a parallel that Trump has drawn before to explain his poor poll numbers — but it didn't make much sense then, and it doesn't offer a real analog today.
Gallup, which was the dominant tracking poll back in 1980 and for years before and after, showed Reagan trailing Jimmy Carter big-time in early 1980. And despite the race narrowing over the summer, it did show Reagan down by 6 points in mid-October, 45-39.
Reagan, of course, went on to win, but that 6-point deficit is less than all but one of Trump's deficits right now.
1948 — Harry Truman
We all remember “Dewey Defeats Truman.” He didn't — but he did squander a late lead, according to the polls.
Thomas Dewey, in fact, led Harry Truman by 5 points, 50-45, in mid-October Gallup polling and wound up losing the popular vote by nearly 5 points.
If there's any ray of hope in all of this for Trump, it's that presidential candidates have swung races by double digits between their worst October poll and Election Day. And Reagan wound up winning by 10 points, so he swung the race by 16 points from mid-October.
But even those swings are from a candidate's worst poll — not the average of polling. FiveThirtyEight's Harry Enten a few days back came at this question a different way, comparing polling averages to the final results. He found the biggest shift was actually in 1992, when mid-October polling averaged an 8.5-point bigger Bill Clinton lead than the final result showed. But that's still not as big as Trump's current 8.9-point deficit, and it wasn't enough to swing that race.
It all suggests a Trump recovery is at least theoretically possible. But these examples all happened during a time when our country was much less polarized. And they involved Truman — an incumbent, with all the advantages of the office — and Reagan, who was Reagan.
Swinging the race in such a big way in 2016 would likely be much tougher.