Radical Republicans tried to impeach Johnson and had considered running someone against Lincoln in 1864. Their own plans for Reconstruction resembled something that the Bolsheviks would try later. An extremely vengeful crowd who would have tried and executed Davis, Lee, and whole passel of Confederates. They lost much of their power when Grant took office. Grant and Sherman and most the Union command had no use for them.
Thanks, that is pretty much my understanding too.