The US Congress was a very cantankerous and divided house leading up to the Civil War. At worst there was years of kicking the can down the road when it came to the subject of slavery, which in retrospect, seems like this problem was inevitably going to blow up, but at the time many people sought to find temporary compromise, and at worst it was openly violent. Senator Charles Sumner was nearly beaten to death by Congressman Preston Brooks in 1856 after Sumner gave a speech about how Kansas should be admitted as a free state. A few days after the speech, Brooks beat Sumner with a cane in the house of representatives Senate. Sumner was from Massachusetts and Brooks was from South Carolina.

There has been violence in the chambers of Congress before, but this is one of the worst incidents. There was a lot of tension and bad blood in the Congress. Many thought Brooks was a hero for nearly beating a man to death.

Edit: Changed House of Representatives to the Senate

David M. Potter in The Impending Crisis : America Before the Civil War paints a very vivid picture of the rancor in the House of Representatives in the year prior to secession. The first session of the 36th Congress in 1859 - 1860 was symbolic of the divisiveness in American politics. This is evident in attempts to elect the Speaker of the House. The northern and southern Democrats had split between Douglas and Buchanan men, pro-slavery and anti-slavery.There were also anti Lecompton men, southern Whigs, Know Nothings and Republicans. The split between the Buchanan and Douglas supporters prevented a Democrat from being elected and they preferred to lose the speakership all together then allow one of the opposing factions to get it. The Republicans could not muster enough support to have their candidate, John Sherman of Ohio elected. Instead they were able to get former Whig and recently turned Republican, William Pennington from NJ elected who supported the exclusion of slavery from the territories, but also was a conservative who supported the fugitive slave law so he was able to pick up some southern Know Nothing support which swung the election in his favor.

This contest lasted two months and showed that the southerners weren't really interested in organizing the House and were willing to paralyze the government. The southern members engaged in protracted and disorderly debate, used dilatory tactics, and allowed 44 ballots to be taken in 40 days of session. They also resisted permitting election of a speaker by a plurality of votes cast. The House was deadlocked from Dec 5 to Feb 1st.

Decorum was evidently thrown out the window during this period as well. Many members had carried weapons. When a pistol fell out of one NY congressman's pocket, the house went nuts thinking he had drawn it intending to shoot. Potter quotes Senator Hammond and Grimes who said, "the only persons who do not have a revolver and a knife are those that have two revolvers," and " The members on both sides are mostly armed with deadly weapons, and it is said that the friends of each are armed in the galleries."

Talk of disunion was rampant if a Republican were to win the 1860 election. The following session was not much different as the Republican party gained strength. Northern Democrats wanted to focus on enacting a new economic program while southern members focused on forcing their pro-slavery territorial views on the rest of the party.

Republicans were able to pass a homestead bill through both houses that ended up being vetoed by Buchanan. They were also able to pass a protective tariff in the House, but not the Senate.