The history of civil rights movements in the United States is basically a series of politicians being pushed to the left—if not dragged there, kicking and screaming.
Even when he was arguing for abolishing slavery Lincoln was initially skeptical that an integrated multiracial society was possible. Just a couple of generations ago you’d be hard-pressed to find any mainstream politicians who would go to bat for interracial marriage or decriminalizing homosexuality. Now they’re so mainstream even the right-wingers pretend to support them.