Marx said, "Democracy is the road to socialism." The attempts after his death to create socialism without democracy proved that totalitarianism is wrong, but they proved nothing about socialism. The socialist objection to capitalist democracy has nothing to do with democracy—it has to do with the fact that capitalist democracy is a government by capitalists for capitalists, as anyone who looks at the average wealth of US Presidents, Senators, or Representatives should be able to tell.
Here's Tommy Douglas's "Mouseland" to show how it works. (This version is in English with Spanish subtitles.)