Southern Democrats affirmed the treaty 10 - 1 , with only one slave state Senator , Thomas Hart Benton , voting against .
Democrats voted for the treaty 15 - 8 , with a slight majority of Northern Democrats opposing .
Democrats   affirmed the treaty 10 - 1 , with only one slave state Senator , Thomas Hart Benton , voting against .
Democrats voted for the treaty 15 - 8 , with a slight majority of Northern Democrats opposing .