Populist Reform of the Democratic Party

Fabian or "revisionist" socialists throughout the 20th Century advocated working within capitalism to transform the system from capitalism to something that would no longer be capitalism -- "Capitalism, . . . will be changed . . . into an order of things which it will be merely a matter of taste and terminology to call Socialism or not," to quote Schumpeter. This was consistently the program of the Socialist Party of the United States before the 1960s. The European Social-Democratic Parties, largely under Marxist influence, in theory rejected both gradualism and Leninism, but their practice was gradualist until the late 20th century. Under the influence of the neoliberal "Washington Consensus" for free-market capitalism those parties pretty much abandoned any attempt to transform capitalism from within by the 1990's; "New Labor," for example.

To the extent that Bernie takes European social-democracy as his model, it is not clear that he envisions any fundamental transformation of the capitalist system into something else. He's old (as I am) and perhaps it is the social-democracy of the 1950's that he has in mind, rather than "New Labor." To transform the Democratic Party into a gradualist socialist labor party would indeed be a "political revolution."

All that said, if DSUSA makes sense for you, go for it.