I'm envisioning a scenario involving a Democratic landslide in 1866 midterms. No Radical Reconstruction, 14th, or 15th Amendments, all states readmitted, no citizenship for freedmen. How does postwar US fare?
A number of things, all of them not good.
For one, I don't believe race equality was at all popular even in the post Civil War US. Republican widely gained power in the immediate aftermath due to the perception that they were the party that "won the war" as well as the memory of Lincoln as well as around the clock attacks on Johnson. The scenario you describe sounds only really possible if a) Lincoln is alive in 1866, or b) McClelland won the presidential election and Democrats are now viewed as the party that "won the war with honor".
Scenario 1:
IIRC, Lincoln had a very concilatory vision of Reconstruction, one that would possibly have him end up not that much different from Johnson. Only this time, the people would see a political party self-imploding upon itself instead of the victorious "Party of the Union" going after a president who was basically still a Democrat. Democrats would then parlay the division in the GOP and show themselves as a united front representing the view of "the people". With strong Democratic majorities in the state and federal legislatures (including Southern states which wouldn't be under military occupation), I imagine they would take the time to portary the Radical Republicans as "a lot of vengeful murderers" or some sort and at times even go as far as to suggest at times that the Civil War was cooked up by the Radicals as an excuse to impose a violent tyranny over the Southern white population so they could tariff the hell out of them like they did the rest of the country. Racist and nativist legislation limiting the presence of non-whites would also likely be suggested on populist grounds of protecting white laborers across the country from the "greedy barons" who would otherwise try to price white workers out of the market.
And given that there are no Constitutional protections for blacks who would otherwise provide early Republicans with a reliable urban voting base in the North to counter Democratic dominance among ethnic whites, I think it is safe to say that there would be a pretty long era of Democratic dominance and the repudiation of the Republican handling of both the war and of their own internal politics might even spell the end of the GOP.
What you would get is basically a white supremacist utopia as even many devout Republicans and advocates of race equality would shy away from race equality for a good long while to please "the status quo". On the flip side there is the possibility of the Democratic coalition cracking a lot sooner than expected as radical agararians in the West and South and immigrant dominated labor unions might fight with their more upper class businessmen brethren in the urban areas.
And then eventually in 2008 the 24th Amendment to the US Constitution would be passed that would end racial segregation in public places.
Scenario 2 will be up later.
