In 1858, Stephen A. Douglas was re-elected to the United States Senate because senators were then chosen by state legislatures rather than by popular vote, and Democratic control of both houses of the Illinois legislature after the election assured his return despite claims that Lincoln had won the popular vote. When the Illinois General Assembly met in January 1859 and cast ballots for senator, fears that four Democratic legislators might defect to support Lincoln proved unfounded. Douglas' Freeport Doctrine grew from his effort to preserve popular sovereignty after the 1857 Dred Scott decision declared the Missouri Compromise unconstitutional and intensified conflict over slavery, and this position helped him hold the Illinois Democratic Party together for re-election even though it opposed the views of much of his national party. The national attention given to the Lincoln-Douglas debates later helped Lincoln gain Eastern abolitionist support, and in 1860 Republicans nominated Lincoln for president while Douglas became the Democratic nominee; southern Democrats, angered by the Freeport Doctrine, split from the convention and nominated their own candidate, while another group also entered a candidate, leaving four men in the presidential race. At Freeport on August 27, 1858, before some 15,000 listeners, the arguments made on slavery and freedom helped shape events that led from Douglas' Senate re-election to Lincoln's election to the presidency and ultimately to the Civil War.