In fact it was mostly blacks with a few white supporters who started the Republican party.
I was just looking at some northern newspapers from 1860, including one from New Haven CT. The articles were talking about how the democrats of the day were fighting against the dissolution of slavery, and how Lincoln was ignoring the economic impact on cities of the North, like New Haven, that would lose revenue as their ports would not be bringing in cotton and other things from the South. The New Haven newspaper, in particular, was slamming Lincoln in favor of the democrat position of the day.
How we ever went from that to the democrats being recognized as the party representing blacks in America is unbelievable. Propaganda is a powerful tool.
Money is powerful too. the blacks are willing to be bought off and feel they deserve reparations.
In fact it was mostly blacks with a few white supporters who started the Republican party.