The Democrats, who used to call themselves "The Party of Personal Liberty", went over to the dark side in 1896 when they nominated the Progressive William Jennings Bryan.
Yeah, I’m making a very rough estimate, given that, Teddy’s proclivities, Wilson’s proclivities, Repub pres in the ‘20s, and everywhere else!
Don’t forget that Teddy Roosevelt, former Republican president, formed a third party because the GOP wasn’t Progressive enough for him. Progressivism afflicted both parties then, and still does today.