You know, for somebody like you, DiogenesLamp, who has with stroke of genius brilliantly figured out that "exports pay for imports", you just as brilliantly can't quite "get" the concept of, the majority of the majority??
OK, then here it is: in a country like ours you don't need to be a majority to rule, you need only be a majority of the majority.
Indeed, when you get right down to it, you can rule as just the majority of the majority of the majority.
In simple numbers, if you have 100 members you need 51 to rule.
A party with 51 members is controlled by its own 26 member majority caucus.
And if you get right down to it, that 26 member majority of the majority is itself ruled by its own 14 member majority, etc, etc.
Of course, all that requires huge, huge, almost impossible diplomatic, managerial & ideological skills and its why such "majority of the majority" control is unstable and changing.
Nevertheless, with Southern Democrats control over the national Democrat party, their rule was much more stable, made so by their common commitment to slavery.
Now 'fess up, DiogenesLamp, did I really have to 'xplain all that to you?
You would have us believe that they controlled the Congress, and had a total commitment to slavery, but for some reason didn't bother voting on a law to extend it to the territories?
Either they didn't have a "commitment" or they didn't have "control."
Your two goofy theories contradict each other, so you will have to pick which one you want to keep, and shoot the other poor bastard in the head.
Let us know which of the two turns out to be the lucky survivor. :)