Like all things political, it's complicated.
One obvious reason is that Douglas was not pro-slavery enough. While he was opposed to abolition, he refused to strongly endorse the Dred Scott decision and other pro-slavery judicial rulings or legislation.
It has also been suggested that pro-slavery secessionists chose not to support Douglas knowing that this would lead to a split in the Democratic party and, effectively, throw the election to Lincoln. Douglas was not vehemently pro-slavery, but he clearly wasn't morally opposed to it. Douglas did claim not to own any slaves personally, but this was a technicality; his wife and children did, and his household benefited economically from them. Lincoln's anti-slavery sentiments are well testified to by both public addresses and private letters, and secessionists felt that a Lincoln administration would soon provide the impetus for the southern states to finally secede.
No, Stephen Douglas is not single.
The original Compromise of 1850 failed to pass the Senate. Stephen Douglas helped Henry Clay by dividing the Compromise into 5 smaller bills and was able to push the bills through the Senate.
Stephen A Douglas
Stephen Douglas debated with Lincoln against slavery
Stephen Douglas won against Abraham Lincoln when running for US Senate
true
John C. Breckinridge. Stephen A. Douglas was the nominee for the Northern Democrats.
Popular sovereignty.
Stephen A. Douglas believed that to keep the presidency in the hands of the Democratic Party, he needed to execute a "southern" strategy. He had to convince southern Democrats that they needed Democratic support in the northern states that gave President Buchanan the White House in 1856. This meant the Democrats had to carry Pennsylvania, New Jersey, Illinois and Indians plus the southern states. Douglas was unable to convince them and southern Democrats focused on sectionalism. This cost them the presidency, and gave the edge to the Republican, Abraham Lincoln. If Douglas had succeeded, there may have not been a Civil War.
Northern Democrats nominated Sen. Stephen A. Douglas of Illinois; Southern Democrats nominated Vice Pres. John C. Breckinridge of Kentucky.
popular sovereignty
Douglas. But Lincoln had gotten Douglas staked out to some positions perceived as pro-slavery in their debates, and this hurt Douglas in 1860 when they opposed each other for president. Douglas was hurt worse in 1860 by the divisions in the Democratic Party, though, which saw southern Democrats nominate and run John C. Breckenridge, and a breakaway faction nominate and run John Bell. So the Democrats divided their vote three ways in 1860, and Lincoln "won" with less than 40% of the popular vote.
they were democrats who supported stephen douglas
Democrat Stephen a. Douglas, John c. Beckinridge of the southern democrats , and John Bell of the New Constitutional Union Party.
stephen douglas
Stephen A. Douglas, US senator from Illinois was their candidate in 1860.
Douglas supported the doctorine of popular sovereignty.