Marxism is currently the system of government in Vietnam, Laos, Cuba, N Korea and China. Russia has tried to implement a capitalist form of government ostensibly but there's an argument whether in fact this is the case. There has never been a Marxist government in the United States, the UK, Sweden, France, Germany, etc. There are those who espouse Marxim in all of these countries just as there are those who support Nazism. No, Democrats are not Marxists nor has there ever been a true Marxist in the US government. Bernie Sanders is a self-described democratic socialist but there is a vast difference between his views and those of a true Marxist like Stalin.
What is your point?