The initial Republican Party was considered radical due to its abolitionist stance since its founding in 1854. However, it was able to rise to predominance and gain popularity in the north, taking advantage of the splintering Democratic and Whig parties. But by the 1860 presidential election, with Abraham Lincoln as its nominee, the party ran on a more moderate diversified platform, advocating for western expansion and development, however abolition was still at the core of the party. Lincoln’s election on November 6, 1860 represented a direct threat to Southerners' use of slaves and acted as the tipping point for several Southern states to secede from the Union, with South Carolina being the first state to secede on December 20th.
Lincoln's election was simply representative of the growing wave of Northern support for emancipation that had already existed years previously. The 1860 election was not in and of itself a cause of the Civil War.
[P1] The Republican Party sought to abolish slavery [P2] Lincoln's election was seen as a direct threat to the livelihoods of Southerners. [P3] This pushed Southern states to secede.
Rejecting the premises
[Rejecting P3] It was not the election itself that caused the secession of the Southern states.