Marx abused alcohol, so not sure. The Republicans are capitalists. The Democrats are capitalists. To Marxists they are the same. Liberalism fails because it cannot address the contradictions inherent to capitalism, inequality and wealth accumulation. Capitalism requires inequality for wealth accumulation.
Social democratic reforms can alleviate the inequality and distribute the wealth more equitably, but, because it does not replace capitalism itself, it always falters.
So, although Democrats and Republicans differ on social policy, they both defer to capitalism. Capitalism rules both parties.