People have tried voting for hundreds of years. Not once has the working class had power, beyond perhaps the brief period of reconstruction before the capitalists in the north worked with the capitalists in the south to put a stop to it. The idea that the DNC can be “pushed left” is based on a belief that the state exists outside of class society, rather than being built upon it. The capitalist state isn’t a capitalist state because capitalists control it, but because it is shaped and reinforced by the capitalist system it rests on top of. You cannot change that by simply changing who runs it.