If I recall correctly, Lincoln was in favor of abolition, while Douglas was in favor of leaving it up to the states.
Lincoln was in favor of a constitutional amendment to guarantee the existence of slavery in the Southern states. However, it wanted it banned in all the territories (although if a free territory wanted to be admitted as a slave state, he would concede that). Douglas was in favor of popular sovereignty, where voters in a territory, either through a direct vote or through an elected legislature or through the formation of a state constitution, would either become slave or free. However, this pissed off the South who felt slaves should be able to brought into any state (Dred Scott).
