[DiogenesLamp]

if someone had won the presidency in 1860 that was going to enforce with Federal forces inside the free states then the free stated would have been in Rebellion

I doubt that. The abolitionists were actually a small minority of the Northern population. Most of the North didn't care one way or the other. Federal Enforcement of the Constitution would have produced some outcry from those people who were that era's version of Liberal kooks, but the rest of the population wouldn't think much about it.

Dred Scott caused the War

Money caused the war. Money and the possibility that the South would become economic competition for established industries in the North.

[Tallguy]

“The abolitionists were actually a small minority of the Northern population. Most of the North didn’t care one way or the other.”

Very true but with one notable exception —Massachusetts harbored a lot of abolishionist sentiments. Harriet Beecher Stowe, William Lloyd Garrison, Frederick Douglass and much of the manpower that became the 5th Massachusetts Infantry Regiment.