The 1860 Democratic National Convention, held in Charleston, South Carolina, and later in Baltimore, Maryland, fractured over the issue of slavery in the territories. Southern Democrats, demanding federal protection for slavery in new territories, walked out when the convention platform adopted a popular sovereignty plank. This split led to the nomination of two Democratic candidates: Stephen Douglas by the Northern Democrats and John C. Breckinridge by the Southern Democrats. This division significantly weakened the party and contributed to the election of Abraham Lincoln, a Republican who ran on a platform opposing the expansion of slavery.
The schism within the Democratic Party proved fatal in the 1860 presidential election. With the Democratic vote split between Douglas and Breckinridge, Lincoln secured a victory despite receiving no Southern electoral votes. This fragmentation is widely considered a key factor contributing to the secession crisis and the outbreak of the American Civil War. The inability of the Democrats to present a united front underscored the deep sectional divisions within the country and ultimately led to the collapse of the existing political order.