The Republican Party was established in 1854 in response to the controversial Kansas-Nebraska Act.  The Act had the potential to expand the reach of slavery into western territories.  The Republican Party wanted to end slavery and was considered the party of abolition.  This attracted the northern abolitionist crusaders, both black and white to the new party.  The Republican Party also attracted many members of the Whig Party, which was deeply divided on the matter of slavery.  The Conscience Whigs were opposed to slavery and quickly enlisted support for the Republican Party.  The Republican Party also attracted the Barnburners, a segment of the Free Soil Party that was strongly opposed to the spread of slavery to new territories.  In general, people that were opposed to slavery supported the Republican Party, which is why it gained little, if any, traction in the Southern States.