It depends what you mean by 'supremacy', really; I think that's a hurdle many people trip up on (and it's probably been made intentionally ambiguous). Do I believe that white people are 'supreme' in terms of their IQ or physical ability or general human worth over other races? No, I don't. Do I believe that white people should be 'supreme' in countries which they built (as in they should maintain a supermajority of the population, and they should dictate the national character)? Yes, absolutely. I believe every race deserves that 'supremacy'.

I don't like to get into these IQ/physical ability/aesthetics contests with other races. I don't really care where white people rank on the totem pole. They're my people, and I would want to preserve them whether they were the dumbest or the most intelligent, as I would expect from any other race.