Lewis, what do you think would happen though if McGovern were elected in 1864?
He would be declared ineligible since he was not yet born.
Lewis, what do you think would happen though if McClellan were elected in 1864?
It depends on why and how he was elected. If it's a ticket of two popular War Generals w/o a Copperhead platform, defeating Lincoln/Thad Stevens, then the war probably continues much as before. Radical reconstruction might actually have happened just as before, if there's a Republican Congress after 1866. There's also the question of what Lincoln does.
With McClellan President and actually calling the shots after the end of the war... one actually wonders whether the South's alignment with the Democrats would ever have happened.
If McClellan totally owes victory to copperheads, yeah, the confederacy would make a getaway for the time being. Of course, slavery was moribund by 1864, as a result of the war more than anything else. And of course, the North would not have given up on the aim of reunification for good. Expect more wars, slave risings, and a much poorer and less important US today. Possibly even a Western secession if Southern independence continues too long. (The spectre of a Mormon
secession, which would have certainly happened had there simply been no war, probably had passed by then.)