Don’t believe me, do your own research. But slave owners were largely Democrats

Here’s a taste from a non-conservative site:

https://en.m.wikipedia.org/wiki/History_of_the_Democratic_Party_(United_States)

Before the American Civil War, the [Democrat] party generally supported slavery or insisted it be left to the states. After the war until the 1940s, the party opposed civil rights reforms in order to retain the support of Southern white voters.