Sheeit. That is dystopic. Sad to see Mac on the bad side of things, but if he's from Arkansas, I guess that's way it had to be. Pretty badass for him to be the major CSA guy this early, though, again, it sucks that he'll be a villain in the history books.
What are the differences between the various Union candidates? Also, how is the party born out of the first Civil War reacting to a second secession? I would hope with bloodlust and vigor. This should be their (literal) call-to-arms.
Everyone except Wilson and Glass support crushing the CAS and winning the war, but the Unionists vary on their civil rights positions (the real debate here is what to do after the war, both w/r/t Reconstruction and in general) - Root's the most pro-civil rights of the bunch, but he's focusing more on economics. Ford's just anti-Semitic, Weeks is an environmentalist, and the other two are pro-civil rights, but less so than Root.
tl;dr if I were you I'd vote for Root or maybe TR if you want to join WWI.
I figured a Civil War would entrench the US in isolationism. However, if the European powers chose to take sides in it, that could be very interesting, especially if a pro-Anglo (like Wilson) or even pro-German (?) President was in office. I could see the Central powers trying to stir up some shyte over here.