Oh you can be mildly racist without being Neo Nazi. I'd be surprised if even 1% of Republican voters were radical enough to be considered Neo Nazi, but I think the number of mildly racist Republican voters is certainly much higher than 1-2%.
Members of organized neo-Nazi organizations are probably fewer than 1%. But there a lot of fellow-travelers under the labels of alt-right, white nationalists, anti-Zionists, Q-Anon believers, anti-Kamala Harris birthers, the plain old KKK, etc. I don't know if they constitute 30% of Trump's base, but they constitute too much of it.
Of course, there are also racists voting Democrat, it's not a uniquely Republican thing.
Yes, there are. Until Trump came along, I was convinced that the Democrats were still the more racist party, just as they had been for the first 130 years of their existence. I think that the Democrats are still riddled with the paternalistic sort of racism displayed by Ruth Bader-Ginsberg when she said that SCOTUS had to keep abortion legal to keep too many black babies from being born. And displayed by rhetoric implying that black Americans are too stupid to wake up in the morning without some agent from the government coming around and setting their alarm clocks for them.
I often wonder what past black leaders--great Americans like Frederick Douglass--would say about today's welfare-state Democrats. Even in his own time, he was saying that the government should leave black people alone--stop hurting, stop helping, "just leave us alone."