But for this issue there was in fact no reason why Curtin should have been stronger in 1860 than Wilmot was in 1857.

Indeed, but for that issue he must have been weaker.

The agitation over the repeal of the Missouri Compromise had somewhat subsided with the lapse of years: the free- State victory in Kansas was acknowledged and that angry issue removed; while the Dred Scott decision, failing to arouse popular resentment at the time it was pronounced, could hardly be effective for an aggressive canvass three years later.

If Governor Curtin could have presented no other issue to the voters of Pennsylvania, he would undoubtedly have shared the fate which Wilmot met when he had these anti-slavery questions as his only platform.

Governor Curtin gave a far greater proportion of his time to the discussion of the tariff and financial issues than to all others combined, and he carried Pennsylvania because a majority of her voters believed that the Democratic party tended to free-trade, and that the Republican party would espouse and maintain the cause of protection.
PENNSYLVANIA'S INFLUENCE IN 1860.
Had the Republicans failed to carry Pennsylvania, there can be no doubt that Mr.Lincoln would have been defeated.