Douglas Democrat refers to those Democrats who supported U.S. Senator Stephen Arnold Douglas of Illinois in the 1860 U.S. presidential election.
The Douglas Democrats were the majority of the party nationally. However, the party became divided over expansion of slavery into the Territories: the western parts of the country which were being settled and would form new states.
Douglas was neutral on slavery expansion, and came to be opposed by southern pro-slavery Democrats.
At the 1860 Democratic National Convention, the minority of pro-slavery Democrats blocked Douglas from getting the 2/3 majority required for nomination. Then most of them bolted the convention. Douglas was nominated by nearly all the remaining delegates.
The bolters formed their own convention and nominated John C. Breckinridge of Kentucky.
Thus, in the November election, there were two Democratic candidates. Douglas received nearly all Democrat votes in the free states - far more votes than Breckinridge - but very few in the slave states, especially the Deep South, and many fewer votes than the Republican votes for Lincoln in the free states of the North.
Douglas carried only one state: Missouri. In New Jersey, where presidential electors were chosen individually, Douglas split with Lincoln.
Soon after the election of 1860, several slave states declared secession, and ceased to participate in the national Democratic Party, which was left to Douglas' followers. However, Douglas himself died in 1861, so the term "Douglas Democrat" ceased to have any meaning.