What was the political atmosphere in the United States in 1860?
In 1860, practically the only political issue of any importance was the issue of slavery and secession. Everything else paled beside that. This was an election year and the election was one that split the country badly. There were four important presidential candidates who differed in terms of the region they were from and their attitudes towards slavery and the Union.
Once Lincoln won the election, the issue shifted to whether the South would secede. South Carolina was the first to secede, leaving the Union before the end of 1860. This left the question of how many other states would secede and what the United States would do.
Because such existential issues were in play, there was no real room for any other topics and the political atmosphere was a highly charged atmosphere centering around issues of slavery and secession.