When a Democrat or any Leftist, accuses you of being a racist, he’s not really accusing you of making decisions based on race, he’s accusing you of being anti-Democrat. Don’t try to reason with him, laugh at him. You can’t reason with a fool, but ridicule actually works.
When they accuse you of being racist in an argument now, you have already won. If they had facts and logic on their side they would use it, but they don’t so they can’t. Same with pulling out the “you’re a nazi” card.