Nonsense, you have it exactly backwards.
Even in 1860 something like 90% of Northerners (along with Lincoln) were content to let slavery exist, unmolested, in the South.
For decades Northerners had helped elect Southern slaveholder Presidents like Democrats Andrew Jackson & James Polk and Whigs William Henry Harrison and Zachary Taylor.
In the 1850s Northerners helped elect Democrat Doughfaced Northerners Franklin Pierce and James Buchanan, men happy to advance the Southern agenda, including a Southern transcontinental rail route and the SCOTUS Dred Scott ruling.
So most Northerners were not opposed to either the South or to slavery, and many understood how much of American prosperity depended on them.
What Northerners did oppose and would not tolerate was the expansion of slavery into US western territories (i.e., Kansas) and even (via the SCOTUS Dred Scott ruling) to their own states.
As Lincoln said in 1858: