Tendency (party politics) in the context of "Militant tendency"

De Leonism, also known as Marxism–De Leonism, is a Marxist tendency developed by Curaçaoan-American trade union organizer and theoretician Daniel De Leon (1852–1914). De Leon was a leader of the Socialist Labor Party of America (SLP) from 1890 until his death, during which time he developed the theory of socialist industrial unionism as a revolutionary strategy.

De Leonist theory advocates dual organization – the simultaneous building of socialist industrial unions in workplaces and a socialist political party to achieve revolutionary change through both economic and political action. This approach distinguishes De Leonism from both Leninist vanguardism and pure syndicalism, proposing instead a "peaceful" revolution achieved through electoral victory combined with workplace organization. The theory envisions workers electing representatives to an "All-Industrial Congress" that would replace traditional government structures, with both the political party and the state ultimately withering away.