What was stephen douglas' stance on the expansion of slavery during the lincoln-douglas debates?

At that time, Stephen Douglas generally support the expansion of slavery. Lincoln initially argue that if they allow the expansion of slavery to happen, it would eventually spread into the free states and revert the progress that the republican party tried to achieve.

Douglas accused Lincoln of wanting to override/overthrow the states authority that excluded black citizens in order to gain more voters to his party in the upcoming election,

Douglas argued for the right of states to decide whether or not to allow slavery.