[BroJoeK]

DL quoting woodpusher: "They were against the spread of slavery to the western territories."

DiogenesLamp: "Where it would not spread.
What they were really worried about wasn't slavery spreading, it was the possibility that territories would turn into states favorable towards the Southern states and thereby affecting the balance of power in Washington DC."

No, in fact, by 1860 slavery was still lawful in the Territories of Kansas, Oklahoma, New Mexico, Nebraska & Utah.
Even California, officially free, still had numbers of de facto slaves.

US States & Territories as of 1860:

Now DiogenesLamp wishes us to believe that Northerners only opposed slavery for economic self-interest reasons and Republicans only opposed slavery for political self-interest reasons.
But the truth is that Northerners first became anti-slavery in their churches, for moral reasons, and culturally through books like "Uncle Tom's Cabin".
Neither of those had anything to do with economic or political self-interest.

[DiogenesLamp]

Now DiogenesLamp wishes us to believe that Northerners only opposed slavery for economic self-interest reasons and Republicans only opposed slavery for political self-interest reasons.

No, that's not what I said. Northerners primarily opposed slavery because they hated black people and did not want black people living among them.

Their second reason to hate slavery was to prevent free labor from competing against their own paid labor.