Former Vice President Joe Biden continues to lead the crowded Democratic field — but under a “ranked-choice” system designed to suss out the majority’s ultimate preference, Sen. Elizabeth Warren would top Biden, 53 percent to 47 percent, according to a new poll exclusively provided in advance to Vox.

The online national poll of likely Democratic voters was conducted by YouGov, and sponsored by FairVote, a nonpartisan advocacy group supporting electoral reform. Unlike an ordinary poll, it asked respondents to rank several candidates in order of preference — so as to simulate ranked-choice voting, a system currently used in Maine and other localities. (FairVote advocates in favor of the system and hopes it will be adopted elsewhere in the US as well.)

The way ranked-choice voting works is that candidates with fewer votes are eliminated, and then their votes are redistributed to whomever each voter designated as their next-ranked preference. For instance, a voter could rank Sen. Bernie Sanders as their first choice and Warren as their second choice — meaning that, if Sanders was eliminated, this vote would be transferred to Warren.

YouGov tested the ranked choice methodology offering all 20 remaining Democratic candidates as options (with the ability to rank 10 of them) — and also by just offering the current top five candidates (Biden, Warren, Sanders, Sen. Kamala Harris, and South Bend, Indiana, Mayor Pete Buttigieg) as options. The end results were quite similar for both versions, so this article will focus on the five-candidate version for simplicity’s sake. (The more extensive results for both versions are available at FairVote’s website.)

In an initial tally counting only voters’ top-ranked choices, Biden leads the Democratic field with 33 percent, and is followed by Warren with 29 percent, Sanders with 20 percent, Harris with 10 percent, and Buttigieg with 8 percent, per the poll.

But it turns out that respondents who initially favored Sanders and Harris prefer Warren over Biden, by about a two-to-one ratio. So once the field is narrowed to a head-to-head matchup of just Biden and Warren, and votes for the eliminated candidates are to whomever each voter ranked higher, Warren would lead Biden by 6 points.

The results are an interesting indication of how an outcome can change due to a different tallying system. But they could also be indicative of something bigger.

Though voters theoretically can choose among many of candidates, we are still months away from a day when primary voters will cast votes. So how voters rank their options in a smaller field could tell us a lot about what the race might look like in the future, and what might happen were the field to winnow further. These results, at least, suggest that Warren would benefit more than Biden would.

Walking through the ranked-choice results

To the uninitiated, ranked-choice voting (sometimes called “instant runoff voting,” or IRV) might seem like a confusing and convoluted system. Our respondents were asked to rank Biden, Buttigieg, Harris, Sanders, and Warren by preference — from first choice, to second, to third, to fourth, to fifth. (If they wouldn’t vote for some of these candidates at all, they could notate that as well.) The graphic below walks through the tally.

A quick note here: The actual counts of voters are rounded from a weighted sample — they’re being presented here to help simulate how the tally would work in a real election, based on these poll results.

What it means

If the topline results of this poll were the results in a typical American election, Biden would just win outright — he got the most first-choice votes in that first tally. But he only has slightly more than a third of the vote among five candidates.

Now, if it was a typical Democratic presidential primary election, it wouldn’t be so simple. That’s because rather than declaring one winner, Democrats allot delegates proportionally to all candidates who get 15 percent of the vote in each primary or caucus. Those delegates go on to cast ballots at the convention.

Ranked-choice can inform a system like that, too. You could cut off the tally once there are only candidates who have 15 percent of the vote or more — to ensure that no votes are “wasted” on candidates who didn’t meet the threshold. In our example above, things would wrap up at the third tally (showing Biden with 39 percent, Warren with 38 percent, and Sanders with 23 percent).

However, at DNC Rules and Bylaws Committee meetings this summer, several members expressed skepticism about whether ranked-choice voting could or should be incorporated into the primary contest given the party’s current rules. And Maine, the state that has most embraced the system, will only use it in the general election next year rather than the presidential primary.

The goal with ranked-choice in general is to ensure the winner is at least in some sense the choice of a majority of the electorate — and that voters who cast ballots for candidates other than the top contenders won’t just see their votes thrown away.

Imagine an election with just three candidates. Candidate A gets 35 percent of the vote, Candidate B gets 33 percent, and Candidate C gets 32 percent. In the most common American voting system (“first-past-the-post”), that Candidate A would just win. But 65 percent of the voters didn’t vote for him — in fact, they might utterly despise him, and have badly wanted him to lose, but been divided between the other two options.

Ranked-choice would avert that outcome: Candidate C would be eliminated, and their supporters would be redistributed to their next-ranked pick. Another benefit is that, under ranked-choice, voters are free to pick an unconventional or underdog candidate as their first choice, without worrying about their vote being “thrown away.”

Of course, there are critiques of ranked-choice voting as well. Simon Waxman has argued that, in practice, the system can be confusing or exhausting — and that the promised majority support doesn’t always materialize, because voters don’t rank enough candidates. (In this YouGov poll, 85 percent of respondents ranked all five candidates — but of course, that also means 15 percent did not.)

Others argue for alternative systems designed to find a “Condorcet winner” — that is, whoever would win a head-to-head race against every other candidate. (It’s at least possible that such a candidate would have little first-choice support and be eliminated quickly under ranked-choice.)

Whatever you think about which voting system is best, for a deeper dive into this poll data, you can head over to FairVote’s website — they have interactive graphics for both the five-candidate result this article discusses, and a separate result in which all 20 candidates were offered as options.