1. Start with the city . . .

Political scientists talk about Duverger’s law, the idea that single-member districts lead inexorably to two-party systems. But Duverger himself recognized that which two parties predominate could vary by region and locale. In Burlington, the two just happen to be Progressives and Democrats, not Democrats and Republicans.

There’s a similar opening in other cities where single-party rule prevails. In New York City, only three out of fifty-one council seats are held by Republicans, and GOP infrastructure is weak. Philadelphia, another effectively one-party town, sets aside two city council seats for non-majority candidates. These spots go to the Republicans simply because there is no left organization like the VPP poised to take them.

New York and Philadelphia are not extreme outliers. Many urban centers in the US are Democratic strongholds that skew ideologically left. Fears of playing the “spoiler” run deep — particularly in the presidential election — and not for nothing. But left-liberal cities under one-party rule naturally avoid this potential pitfall, giving the Left a clear opportunity to make electoral gains.

In short, there is no reason why many cities in the US can’t become two-party towns — dominated not by Democrats and Republicans, but by socialists and Democrats.

2. . . . or start small.

Political scientists also tell us that canvassing can substantially boost voter mobilization. In rural states like Vermont, direct engagement with residents can have even bigger payoffs, allowing third parties to overcome financial and logistical barriers and increase name recognition.

Indeed, the VPP has been able to establish a base partly because Vermont is a small state. Many VPP candidates claim to have personally knocked every — or almost every — door in their districts. That’s simply not possible in big cities.

Part of the Bernie Sanders story is that a crew of socialists built power in a small pond and then, in 2016, leapt into the ocean. While socialists tend to congregate in cities, one lesson of the VPP is that the Left should look for openings in smaller and more rural states. Even Wyoming has two Senate seats.

3. Build a party identity.

In an era of increasing voter antipathy toward both major parties, the Progressive label can seem unsullied and more attractive to disaffected voters. As VPP elections director Josh Wronski put it: “We are able to get attention because we are not the Dems.”

Yet even in the age of independents, party identification still often shapes voting behavior, over and above other factors. This presents obvious challenges for a third-party formation like the VPP: it has to foster a Progressive identity, different from that of the Democrats and Republicans, among the party rank-and-file and the voting population more broadly.

It’s had some success. One Progressive I talked to said that in response to Democrats who tell people they are “small-p progressives,” she now says, “I’m a big-P Progressive, small-d democrat.” Another party activist told me that, door-knocking in Burlington, you come across second- and even third-generation Progressives.

It may be some time before Kshama Sawant, the Seattle socialist city councilor, is able to claim any second-generation socialists in the city. And the VPP seems more interested in fostering a capital-P Progressive identity than a broadly socialist one. But leftists shouldn’t underestimate the importance of creating new partisan attachments.

It’s one thing for a majority of city councilors to be “independent” of Democrats and Republicans. It’s quite another when Progressives control an entire city council.

4. Know the rules.

In Vermont, many districts for state office are actually multi-member. The most electorally savvy in the VPP quickly learned, however, that this was not necessarily to the party’s advantage.

VPP voters were less likely to “bullet vote” (i.e. select just one candidate, even if given the option to choose more than one) than their Democratic Party counterparts. If one Progressive was running in a two-seat district, for instance, most Progressives would vote first for their candidate and then for a Democrat. Democratic voters were more apt to back two Democrats. As a result, even a very popular Progressive candidate could end up coming in third.

Pursuing electoral reform was one way to mitigate this problem. But in the immediate term, VPP developed “sponge candidates” who would get on the ballot simply to absorb the second Progressive vote, thus preventing it from going to a Democrat.

The lesson here is not that the Left needs to study the boring details of Vermont electoral law, but that the Left needs to study the boring details of local electoral law wherever they are active. In every place we see successful third parties, we see a group that has taken the time to examine the legal minutiae.

5. Address the fusion dilemma.

Vermont has what is called “partial fusion” — candidate names are listed once on the ballot, and parties are listed after their names. The candidate signals the party with which she will caucus by the order in which the parties are listed. This is distinct from “full fusion,” like in New York, where a candidate’s name is listed under each party that has nominated her.

Electoral fusion has a long history. In the 1890s, the People’s Party was on the rise, in part thanks to the successful use of a fusion strategy. They challenged the major parties where they could win, and accrued name recognition where they couldn’t.

At the time, fusion was legal everywhere. But before long, Republicans — afraid the tactic would spell its demise — passed legislation outlawing fusion balloting in states throughout the country, beginning in the Pacific Northwest. Today, the only places where fusion balloting remains legal are the states where such legislation never arrived (save for Oregon, the only state to have re-legalized fusion balloting and where the Working Families Party now operates with notable influence).

Many VPP activists think of themselves as to the left of the WFP, and given the party’s history and the Progressive versus Democrat battles that still play out in Burlington, this is no surprise. But at the state level, the VPP’s approach looks much like the WFP’s: push Democrats to the left using fusion voting.

For some, the VPP’s fusion strategy represents a break with the party’s core mission that subordinates it to the Democratic Party. Party officials, by contrast, are confident their candidates are of a different breed when they reach elected office. They point to the statehouse caucus as evidence — P/Ds and Ps meet separately from Ds, and tend to champion more social-democratic legislation.

Whether leftists in other cities and states adopt a similar strategy will depend on local conditions. But evaluating the contexts in which fusion may be justified will be a key task. On this and other strategic issues post-Bernie, hardheaded thinking can’t be in short supply.