With Malice Toward None: The Life of Abraham Lincoln, by Stephen B. Oates. It's very good. And instructional. If there's one thing that everyone who knew Abraham Lincoln agreed on, it's that his integrity was unimpeachable. Ah, for a politician that couldn't be bought! It's interesting to see, though, that Lincoln really was a politician. He was, at times, a partisan hack. Just an honest partisan hack. That makes all the difference. Also, for all the weirdness you hear about Abraham Lincoln's marriage, they evidently loved each other very much (so far anyway. I'm only to 1860). And Lincoln was a slob. He kept documents for his law practice in drawers, on tables, in boxes, in his stovepipe hat (apparently all kinds of stuff got stashed up there-- his partner said it was "[Lincoln's] desk and memorandum book), and in a little packet on his desk marked "when you can't find it anywhere else look into this". Neither he nor his partner Herndon ever bothered sweeping, and Lincoln liked to eat fruit like oranges and cherries for lunch and then spit the seeds on the floor. One law student who had been in their office said that the floor was so literally dirty that some of the seeds actually sprouted.
Politics right before the Civil War were explosive. Congressmen were duking it out on the House floor in Congress, showing up drunk for votes, and threatening the opposite sides with predictions of the end of American civilization if what they wanted to happen concerning slavery failed to come to pass. Probably not too different from now, other than I don't recall a recent fist fight.