The oldest political dispute inside the US left isn’t going away anytime soon. Revelations about the Democratic National Committee’s pro–Hillary Clinton intrigues and local victories for leftists in the November elections have added fuel to the fire of that age-old question: how should socialists confront the two-party system?

On one side, supporters of “realigning” the Democratic Party insist that given the constraints of the US political system, transforming the party is the sole viable strategy for progressive politics. On the other side, advocates of a clean break from the Democrats and Republicans see any involvement within capitalist parties as an unprincipled dead end.

Proponents of each stance can rightly point to the practical failures of their rivals’ approaches over the past century, especially at the national level. But both sides have ignored the example of the most electorally successful workers’ party in the history of the United States — the Minnesota Farmer-Labor Party (FLP).