“Stronger” fugitive slave laws apparently means non-enforcement or repeal of the Northern states personal liberty laws. If Lincoln had given the slave states that it would have torn the North — and the Republican Party — apart. Could Lincoln have done it? Would he have? Northern states weren’t likely to repeal their laws, nor was Congress likely to deliver even stronger fugitive slave laws. Lincoln was repeating his commitment to enforce existing laws. He was also making a last minute offer to save (what was left of) the Union. The militant secessionists who controlled the Deep South easily saw through the offer. It wasn’t something Lincoln could make happen and it would have doomed his presidency if he had tried.
Well put. In the North, public sentiment strongly favored fugitive slaves, even to the point of crowds gathering to impede the efforts of slave catchers. Alert Southern slaveholders realized well enough that effective enforcement of fugitive slave laws in the North had become impossible by the time of Lincoln’s election.
Like Illinois, where you could sell any black person into slavery if they didn't have their paperwork proving they were free?