Harrison was an early advocate of the Georgist economic philosophy and later clarified that he had believed Georgism was the same thing as socialism. In 1911, after his postal firing, Harrison began full-time work with the Socialist Party of America and became America's leading Black Socialist. He lectured widely against capitalism, campaigned for the party presidential candidate Eugene V. Debs in 1912, and founded the Colored Socialist Club (the Socialist's first effort at reaching African Americans). He developed two important and pioneering theoretical series on "The Negro and Socialism" for the socialist newspaper the "New York Call" and for the socialist monthly "International Socialist Review". In these articles Harrison outlined a materialist analysis of racism, arguing that it resulted from "the fallacy of economic fear" and economic competition, and that capitalists had an interest in maintaining economic discrimination based on racism, as "they can always use it as a club for the other workers". He maintained that it was the principal "duty" of the Socialists to "champion the cause of the African American and that the Socialists should undertake special efforts to reach African Americans as they had done with foreigners and women." Perhaps most importantly, he emphasized that "Politically, the Negro is the touchstone of the modern democratic idea" and that true democracy and equality implies "a revolution... startling even to think of."