But he was absolutely 100% opposed to that.
Slavery could not "expand" to new territories. You could not grow cotton in any of the territories, and that was the absolute primary usage of slaves in that era.
The claim that it would "expand" was a lie meant to scare people. What they were really afraid would "expand" was the possibility of states coming into the Union that would be allied with the Southern states, and therefore help them repeal the corrupt and unfair laws that had the Southern states paying 72% of all the taxes.
The "expansion" claim was just a political lie and people are still swallowing it today.
Perhaps but exactly what could Lincoln do in regards to the new territories and the decision on whether free or slave or choice? Heck I think he was a lawyer when that passed.
We must also remember, that by the time Lincoln took office the south had already succeeded. Much based on what they thought Lincoln might do, not what he had done.
While slavery and states rights ect were certainly a part of our civil war, dig deep and you will find the high European financial powers dirty fingerprints all over it. 25 years earlier we had rid ourselves of the second national bank and since then we were doing well, without the central bank, while expanding westward. This was something the central bankers could not allow.
Take this quote from Otto Von Bismark, the man that would a few years later unite Germany:
“The division of the United States into federations of equal force was decided long before the civil war by the high financial powers of Europe. These bankers were afraid that the United States, if it remained as one block, and one nation, would attain economic and financial independence, which would upset their financial domination over the world.”
Within months of Ft Sumpter the bankers loaned Napoleon III of France 210 million franks to invade Mexico and station troops along our southern border. At the same time England parked 11,000 troops on our northern border and put their fleet on war alert.
Lincoln was in a tough spot, much tougher than most realize. Saving the union, at this time in our history, stretched well beyond the north/south dispute. Had we stayed fragmented we may well have fallen piecemeal.