The Communist Manifesto is a warning about the failure of capitalism and a rough draft of a form of government which might evolve when capitalism failed. Lenin tried to implement textbook Marxist Socialism and failed. It turned into a nightmare totalitarian regime that cost millions of lives. Nobody is looking to go down that path again.
Our Constitution prohibits that sort of government overreach anyway. We are ruled essentially by the Lockean Theory which overrules(wisely) some of the tenets of Marxist Socialism. It does not, however, overrule Social Democracy. In fact I think John Locke would heartily approve of it. So would Marx and Engels.
Social democracy is a political, social and economic ideology that supports economic and social interventions to promote social justice within the framework of a liberal democratic polity and a capitalist economy.