How to depolarise American politics

More than ever before, Americans are dissatisfied with their two main political parties, the Democrats and the Republicans. In a recent Gallup poll, 63 per cent of respondents – the highest percentage ever – said “a major third party is needed.”

Yet with voters so polarised, America’s conventional first-past-the-post electoral system (each voter casts a ballot for a single candidate, and the candidate with the most ballots wins) prevents a third-party candidate from posing a serious challenge, even if he or she can bridge ideological divides. Democratic voters may greatly prefer a third-party candidate to the Republican, but they will still cast their ballot for the Democrat given their strong partisan preferences; Republican voters will act symmetrically, in the opposite direction. Only a sliver of independent swing voters will end up voting for the third party.

Fortunately, a variant of California’s top-two system would solve this problem and allow a moderate third-party candidate – a nominee offering a compromise between political extremes – to compete successfully. As in California, all candidates – regardless of political affiliation – would compete in a nonpartisan primary, with each voter casting a ballot for one of them. But, unlike in California, the top three (rather than the top two) vote-getters would advance to the general election.

Then, on Election Day in November, voters would express their preference between each pair of candidates on the ballot. Thus, a voter chooses between A and B, between A and C, and between B and C. The winner is the candidate who defeats both opponents: A would win if more voters choose A over B than B over A, and if more select A over C than C over A.

To see the advantages of such a system, consider Ohio’s 2022 US Senate race. The general election was a contest between the Republican J.D. Vance, who had been endorsed by former President Donald Trump, and Democrat Tim Ryan, which Vance won. The traditionally conservative incumbent, Rob Portman, declined even to run, because he saw that he would lose to the Trump-endorsed candidate in the Republican primary.

But suppose Ohio had used a top-three system. Portman would probably have chosen to run in the nonpartisan primary (where he wouldn’t need the Republican party’s nomination to be on the ballot), and the general election likely would have featured him, Vance, and Ryan.

On the part of the ballot pitting him against Vance (A versus B), Portman most likely would have won (say, by 54 per cent to 46 per cent), owing to the combined support of non-Trumpist Republicans, independents, and Democrats. And, against Ryan, he would have had all the advantages of a popular incumbent senator in a conservative state (winning by, say, 60 per cent to 40 per cent). Presumably, Vance would defeat Ryan by about 57 per cent to 43 per cent, as he did in the actual election; but only Portman would have defeated both opponents, because he was the candidate whom a majority of voters preferred over each of the alternatives.

This outcome underscores the inadequacy of the prevailing voting system, where Portman couldn’t even survive the Trump-dominated Republican primary. But it also reveals the shortcomings of California’s top-two method, where polarization would probably have ensured that only Vance and Ryan advanced past the primary.

Of course, we have been assuming that some candidate (Portman, in the Ohio example) will emerge as the majority winner in both pairwise comparisons, because both theoretical and empirical work suggest that this is by far the most likely outcome. But it is conceivable that there would be no such candidate. Suppose against all odds Ryan manages a squeaker win against Portman, 51 per cent to 49 per cent. In that case, there would be a three-way tie with each candidate defeating one of his opponents, but nobody defeating both. We would need a tie-breaking rule to determine the winner. One attractive option is to elect the candidate who loses by the smallest margin. The victory would go to Portman, who loses by a margin of only 2 per cent to Ryan.

Many voting-reform advocates will ask why the general election shouldn’t just use ranked-choice voting (as Maine and Alaska already do for congressional elections). In an RCV system, voters rank all the candidates on the ballot from most- to least-favoured. If a majority ranks one candidate first, that candidate wins. If not, the candidate who was ranked first the least often is dropped and the process repeats until a majority is reached.

This approach does have its attractions (and we are proponents of it). But it is incapable of bridging the polarisation gap. In a general election involving Vance, Portman, and Ryan, we would expect strong partisanship to give Vance and Ryan first-place percentages higher than Portman’s. According to the RCV protocol, Portman would be dropped first, despite beating each of the other two in head-to-head matchups.