The problem they have is that communism was a real enemy of the US with examples of autocratic governments worldwide that were well known and scary to people.

However, now that everyone can Google "what is communism" and "what is socialism" only the most incurious morons fall for the "that's socialism!" lines of attack. Everyone else simply laughs about it.

It really doesn't help that Republicans are openly talking about how they want to setup and autocracy/monarchy which is exactly the scary part of former/current communist states. Nor does it help that whenever Republicans are labeling something communist, it's loved social programs such as libraries, social security, or Medicare.