Why Washington State’s Primary Results Offer a Cautionary Tale for London’s Electoral Reform Debate

Londoners debating the future of the Greater London Authority’s electoral system should pay close attention to the results of Washington State’s August 2026 primary elections. The data shows a clear public appetite for multiparty representation that the existing top-two voting system cannot fully accommodate. While the geography and institutions are different, the structural problem is directly comparable to concerns raised about the Supplementary Vote system used for London’s mayoral and Assembly elections.

What the Washington primary revealed

According to analysis published by The Urbanist on 29 August 2026, primary voters in Washington State effectively supported three distinct political blocs: establishment and moderate Democrats (40% of the statewide congressional primary vote), Republicans (35%), and an emerging left-wing party comprising progressive Democrats, Democratic Socialists of America (DSA) members, and independent left-wing candidates (20%). The analysis, conducted by examining candidate websites, rhetoric and policy platforms, found that left-wing candidates prevented four incumbent Democratic congresspeople from reaching 50% of the vote in Western Washington districts.

In Eastern Washington’s Fifth Congressional District, incumbent Republican Michael Baumgartner received just 47.4% of the primary vote, with the remaining 52.6% split between mainstream Democrats, progressives and independents. Independent candidate Nate Powell finished third with 16.5% of the vote and subsequently endorsed the Democratic challenger Carmela Conroy, illustrating the coalition-building that top-two systems force upon voters.

The top-two system’s limitation

Washington State uses a top-two primary system where all candidates, regardless of party, appear on the same ballot. The top two vote-getters advance to the general election, regardless of party affiliation. This system, similar in some respects to the Supplementary Vote used for London’s mayoral elections, is designed to produce a two-candidate runoff. But as the primary results demonstrate, voters are not thinking in binary terms.

The Urbanist analysis notes that over one-quarter of primary voters chose either a left-wing or independent alternative to the two-party system. In Seattle’s 37th and 43rd legislative districts, voters effectively operate within a two-party system of moderate Democrats versus progressive Democrats and DSA candidates. The results show that the left-wing faction is establishing itself as a distinct political force, not merely a wing of the Democratic Party.

Why this matters for London

London’s Supplementary Vote system for the mayoralty and the Additional Member System for the London Assembly have long been criticised by electoral reform advocates for failing to translate voter preferences into proportional representation. The 2024 London Assembly elections saw the Conservatives win 21.9% of the constituency vote but only 8 of the 25 seats (32%), while the Liberal Democrats won 11.4% of the constituency vote but only 2 seats (8%). The Green Party won 7.9% of the constituency vote but only 3 seats (12%).

The Washington primary results offer a real-world example of how voters behave when presented with more than two viable choices, even within a system designed to compress those choices into two finalists. The data shows that voters do not simply vote strategically for the lesser evil; they support candidates who represent their policy preferences, even if those candidates have no realistic path to victory under the current rules.

Voter turnout as a warning sign

A critical data point from the Washington primary is voter turnout. Just 37% of registered voters participated in the 2026 primary, down from more than 40% in the 2022 and 2018 midterm primaries. The Urbanist analysis attributes this decline partly to political cynicism driven by the top-two system’s artificial limitation of choice.

London’s mayoral election turnout has also shown signs of fatigue. The 2024 mayoral election saw turnout of 40.5%, down from 42.2% in 2021 and 45.3% in 2016. While direct comparisons are difficult, the Washington experience suggests that when voters perceive their choices as effectively predetermined, they are less likely to participate.

Proportional ranked choice voting as an alternative

The Urbanist analysis advocates for proportional ranked choice voting (RCV) as a solution. Under proportional RCV, voters rank candidates in multi-member districts, and seats are allocated proportionally based on vote shares. This system is already used in some form in cities such as Cambridge, Massachusetts, and for national elections in countries including Ireland and New Zealand.

For London, a shift to proportional RCV for the London Assembly would mean replacing the current mixed system with multi-member constituencies where voters rank candidates. The Green Party and Liberal Democrats have both called for electoral reform at the GLA level, though the Labour and Conservative administrations have shown little interest in changing a system that has historically benefited the two largest parties.

What remains unclear

The Washington primary results do not directly model how a proportional RCV system would function in London. The political landscape, party structures and voter behaviour are different. The Urbanist analysis is an opinion piece, not a peer-reviewed study, and its categorisation of candidates into left-wing and moderate blocs is based on the author’s own assessment of campaign rhetoric and policy platforms.

It is also unclear whether Washington State voters would actually prefer proportional RCV to the current system. The primary results show support for multiparty politics, but no referendum or binding vote on electoral reform has been held.

How Londoners can engage

For Londoners interested in this debate, the most practical next step is to examine the London Assembly’s current electoral system and compare it with alternatives. The London Assembly has published its own review of the 2024 elections, which includes data on vote shares and seat allocations. The Electoral Reform Society also produces regular analysis of UK electoral systems, including the GLA’s.

The Washington primary results do not provide a direct blueprint for London, but they do offer a compelling case study of what happens when voter preferences outpace institutional design. As London’s political landscape becomes more fragmented, the question of whether the current electoral system adequately represents the city’s diversity of opinion will only become more pressing.

Source: The Urbanist, “Op-Ed: Washington’s Primary Election Results Underscore the Case for Proportional Ranked Choice Voting”, published 29 August 2026, available at https://www.theurbanist.org/op-ed-washingtons-primary-election-results-underscore-the-case-for-proportional-ranked-choice-voting/. Additional turnout data from the Washington Secretary of State and the London Elects website.

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