Communism is government ownership of the whole production, economy and unions. This is the definition -- nothing else. Republicans try to tag anything that isn't Republican "marxist". They're actually the most 'marxist' party in the U.S. Nobody else is issuing Marx in our national politics, but the Republicans. I don't wonder. Reagan's union policy was flat-out communistic. He called worker unions unnecessary, because his government would know what was good for workers. The same argument as in the Soviet Union of that time, in order to do away with free unions.
Karl Marx was a German philosopher and author in the 19th century. He has nothing to do with the United States today. Marx himself was NOT a "marxist"; the fact that people made an ideology out of his work did not please him. In France he once replied to a 'marxist': "Je ne suis pas marxist" (I'm not a marxist).
What has our president in common with a German philosopher and author, who watched and described the situation of workers in his time? Nothing! Marx' describing was spot-on. He was the first who saw and issued those problems. He also tried a prognosis and uttered some ideas to improve society. In his later years he saw, his prognosis did not come true. Well, the 'marxists' of his time were not as smart as Marx, and they weren't smarter during the 20th century as well. Whatsoever, 'marxism' is non-existent : Karl Marx just published books and didn't care to create a dogmatic ideology. Today his stuff is history, because the situation in modern societies has changed.
You can define communism, via Communistic Manifest. The U.S. were in great danger to slip into a communist regime during the 30s depression. Thanks God, FDR's new deal prevented this. Today there is no communistic threat inside the U.S. -- people who still call themselves "marxists" are a very small minority. The threat of our time is libertarianism and comes directly from the Republican party. Libertarianism is an anarchistic form of communism and just as dangerous as 'marxism' (although there actually is no marxism, but in the stupid talking points of the GOP).
If you hear one of those GOP hicks, possibly with Texan accent, talk about Marx, you know there's actually a relationship between libertarianism and marxism. Both use anarchy to establish oligarchy.