The stack exchange code of conduct clearly states bigotry is not acceptable:
No bigotry. We don’t tolerate any language likely to offend or alienate people based on race, gender, sexual orientation, or religion — and those are just a few examples. When in doubt, just don’t.
On most stacks this is straightforward, however, politics involves understanding potentially odious viewpoints. Obviously bigoted name calling is inappropriate, but sometimes a bigoted position has to be discussed to better understand the politics of what is going on. On this meta question, a user suggested
However, politics.SE is bound to the Code of Conduct of stackexchange, which forbids bigotry.
If an answer uses white supremacist sources, I would flag it and maybe additionally use the "Contact us" option to make sure the appropriate action is taken.
I'm not sure whether this is the right approach or not. If someone asks the on-topic question "What positions does political group X take on social issues?" If group X is a bigoted group, it probably makes sense to answer:
"Group X believes in bigotry based on race, gender, sexual orientation, and religion. The leader of group X [said] (bigoted website) this bigoted thing 'bigoted thing.' Members of group X agree with this bigoted idea based on [this poll] (source). Group X cites bigotry as the basis for these policies..."
I wouldn't say that answer is likely to offend at all, since it is purely descriptive and doesn't take a normative position. However the standard is set very high with "if in doubt, don't" and it's hard to say what might offend any of the global audience of a website. Is it appropriate to neutrally explain the viewpoints of groups whose stances violate stack exchange's code of conduct?