Civil rights didn't surface as a political priority until the mid 1950s. The dems made the political decision to rebrand and embrace it. The opposition came f/ the GOP and the south. MANY people switched party over this highly charged issue. It's how the south became so red today.
Strom Thurmond is symbolic of the transition.
"A magnet for controversy during his nearly half-century Senate career, Thurmond switched parties because of his support for the conservatism of the Republican presidential candidate Senator Barry Goldwater. In the months before switching, he had "been critical of the Democratic Administration for ... enactment of the Civil Rights Law", while Goldwater "boasted of his opposition to the Civil Rights Act, and made it part of his platform.""
This led to the southern strategy.
"In American politics, the Southern strategy was a Republican Party electoral strategy to increase political support among white voters in the South by appealing to racism against African Americans."
Martin Luther King weighed in on the Republican party during his lifetime. In Chapter 23 of his autobiography, King writes this about the 1964 Republican National Convention:
"The Republican Party geared its appeal and program to racism, reaction, and extremism. All people of goodwill viewed with alarm and concern the frenzied wedding at the Cow Palace of the KKK with the radical right."
I'm old enough to remember all this. Righties will deny history as recorded before they will admit what they know is bad for business. They will never fix their racism problem w/ denial because admission is the first step to recovery.