But what if it did happen, and what does history tell us about the possibility?
Adams’s lead over Maya Wiley, who is in second place, stood at 31.7 percent to 22.3 percent — 9.4 percentage points — with results in from 84 percent of precincts. It could take weeks to count all of the votes, including absentee ballots and then to pare down the field by gradually eliminating one candidate at a time until only two remain. But Adams’s lead would seem to be rather secure on its surface.
That’s because no candidate in any American ranked-choice race has overcome such a deficit before.
The election reform group FairVote, which advocates for ranked-choice voting, has crunched the numbers on previous come-from-behind wins in ranked-choice voting. It has found that, since 2004, only in 3.8 percent of cases has the winner of a single-winner race not been in first place after the first round.
Of 15 races in which a candidate has come from behind to win, the largest deficit overcome was 9.3 percent — just shy of Adams’s current lead. That race was the 2010 Oakland mayor’s race.
It bears emphasizing that Adams’s lead could change somewhat as the final first-round ballots are counted, including absentee votes that might aid Wiley or Kathryn Garcia (in third place at 19.5 percent). But even if it were to shrink by a few points, it would still very uphill. In only five out of 400 races has a candidate overturned a first-round deficit of more than five points.
That said, bigger shifts are plausible — and have happened.
In that Oakland race, for instance, the shift in the margin was 11.3 points in total — from down 9.3 percent to winning by two points.
Perhaps the most cited example of such a big shift was another big-city California mayor’s race, in San Francisco in 2018. In the race, Democrat London Breed’s 12.2 percent lead in the first round was reduced to just 1.1 percent by the end. She even trailed for a period. Second-place finisher Mark Leno didn’t come from behind to win, but he did make up more than 11 points from first round to last — similar to what happened in Oakland and enough to erase Adams’s current lead in New York.
Those are two of the biggest overall shifts we’ve seen from first ballot to last in come-from-behind scenarios. But we’ve also seen double-digit shifts in four other come-from-behind wins, including a 2017 Minneapolis City Council race that shifted by a whopping 17.8 points.
Now for the caveat: There was something of an unusual setup in each of those races that we don’t necessarily see in New York.
Leno was one of two progressive candidates fighting for the same lane, while Breed mostly had the pro-business lane to herself. It was thus understandable that Leno would make up a huge amount of ground in later rounds, when the other progressive candidate was eliminated.
Similarly, in the Oakland race, initial leader Don Perata was a conservative Democrat, and many of the other candidates, including the ultimate winner, Jean Quan, teamed up to form an “anybody but Don” coalition.
In the race with the biggest shift, in Minneapolis, the state Democratic Party’s endorsed candidate, Steven Fletcher, initially trailed a member of the Socialist Alternative movement. But he benefited substantially (and understandably) when another more mainstream, business-oriented candidate was eliminated.
The lanes in New York’s crowded mayoral primary don’t seem to be nearly as neatly defined ideologically, nor did we see such an overt attempt to team up against Adams. The alliance that the Adams campaign cried foul about was between third-place Garcia and fourth-place Andrew Yang, but even that was somewhat tentative and last-minute.
What’s more, the pre-election polling we had on the race suggested smaller shifts between first round and last than would currently be required, depending upon who the final two candidates are. In a final matchup between Adams and Wiley, Adams actually gained, on average.
That doesn’t mean Adams can’t lose. The Post’s Philip Bump looks at this from another important angle: which candidates finished second in each electoral district. (Basically: Wiley was second in a lot of them, which might suggest she’s more likely to be the second choices on voters’ ballots. But she was also second behind Adams in a lot of those, which might suggest less of an advantage if it comes down to the two of them.)
But it’s a history worth examining — and one that will increasingly be at issue as more of the country adopts ranked-choice voting.