The Northern states supported the Republican Party that was formed in 1854. The party was founded by anti-slavery Whigs who convened in the upper midwestern states on October 20, 1854.
The Republican Party was established by former Whig Party members to counter slavery in the western territories. The Whig Party later disintegrated due to the dissolution of the Missouri Compromise, which eventually led the formation of the Republican Party.
The new party garnered tremendous support from the North. John Fremont, the party's first presidential candidate, secured the majority of the votes in 11 out of 16 states, but eventually lost. The victory of the first Republican president, Abraham Lincoln, in the 1860 elections triggered the secession of the Southern slave states from the Union.