Look, where you can actually achieve things is in the Democratic primaries. Find the furthest left person you can and try to make them the candidate. Move the party left. Get your brand of politician onto the ballot on one of the teams that can win. Replicate that across the country and I guess the Democrats become communists, though I can’t imagine things flipping that far. You still have to deal with swing states that will be much harder to get communist candidates elected even in a major party.
That’s the only realistic way to accomplish your goal without either waiting for one party to commit suicide or futilely taking up arms to try to replace the whole system of government.
That’s not even my political persuasion, but look I’ll be long dead before that ever happens so more power to you. We’ve swung way too far right and I’ll work with anyone to swing it back the other way.