Answer:
The issue of slavery was largely responsible for the party realignment that followed the election of Abraham Lincoln in 1860.
Step-by-step explanation:
In the presidential election of 1860, Abraham Lincoln was elected 16th President of the United States of America.
There were four major presidential candidates, Abraham Lincoln, who stood for the Republicans, John Cabell Breckinridge for the Southern Democrats, Stephen Arnold Douglas for the Northern Democrats, and John Bell for the United States Constitutional Union, which had formed from the Whigs.
Since the Republicans were in favor of the abolition of slavery, southern states declared their independence in the months following the election and joined forces with the Confederate States, leading to the Civil War.