In addition to this, comparing Austria and Germany, which both are multi-party systems, to a two-party system like the United States is problematic in this context. A significant chunk of the GOP and their voters likely support the same policies that the Freedom Party or the NPD support, but it's much harder to label or quantify that group.

Which is why I used active members and the Southern Poverty Law Center as well as voting numbers.

These numbers aren't comparable. You're equating membership of an actual Nazi group with being a member of a far-right party with historical ties to Nazis. A much more apt comparison to these parties would be to look at members of the GOP who support far-right policies, but that's hard to quantify.

FWIW, I don't have a particularly strong opinion on whether laws banning Nazi speech have a large impact on the number of people supporting that ideology. I don't think they increase the number of Nazis, and it makes sense to keep them around given the historical context of countries like Austria and Germany even if they don't have an impact on that number.

I do think you're quite far off the mark if you think less than 0.001% of the U.S. population identifies with Nazi ideology, while it's something like 1% for Austria and Germany.

I don't think the GOP/NDP comparison is apt, because Germany attempted to ban the NDP completely and the NDP works continuously with literal Nazis. If the KKK had a political party of its own, that would be comparable. There are only a few thousand members of the KKK left, though, so that is unlikely to occur.

I think that for the same percentage to identify with Nazi ideology it would require millions of people to be so comfortable with it that they would openly give Nazi affiliated parties their support.

I don't think millions of people support Neo-Nazis in the US.

None of those people are currently serving in any capacity in Congress and almost all of them are dead. I don't deny that the KKK was big in the US and had political power in 1926.

Also, The Southern Poverty Law Center estimates that there are 190 active KKK groups with between 5,000 and 8,000 Klan members in the U.S. That's a far cry from Austria and Germany.