The Dred Scott decision declared in terms that Congress could not prohibit slavery in Territories nor authorize a Territorial Legislature to do so.

The Dred Scott decision had thus annihilated "popular sovereignty," Would Douglas admit his blunder in law, and his error in statesmanship?
He had already faced and partly evaded this dilemma in his Springfield speech of 1857, but that was a local declaration and occurred before his Lecompton revolt, and the ingenious sophism then put forth had attracted little notice.

Since that time things had materially changed.

He had opposed Lecompton, become a party recusant, and been declared a party apostate.

His Senatorial term was closing, and he had to look to an evenly balanced if not a hostile constituency for reelection.