Trumbull was an antislavery Democrat, and had received few votes in the earlier ballots; his supporters, also antislavery Democrats, had vowed not to support any Whig. Lincoln's decision to withdraw enabled his Whig supporters and Trumbull's antislavery Democrats to combine and defeat the mainstream Democratic candidate, Joel Aldrich Matteson.[112]

1856 campaign
Violent political confrontations in Kansas continued, and opposition to the Kansas–Nebraska Act remained strong throughout the North. As the 1856 elections approached, Lincoln joined the Republicans and attended the Bloomington Convention, which formally established the Illinois Republican Party. The convention platform endorsed Congress's right to regulate slavery in the territories and backed the admission of Kansas as a free state. Lincoln gave the final speech of the convention supporting the party platform and called for the preservation of the Union.[113] At the June 1856 Republican National Convention, though Lincoln received support to run as vice president, John C. Frémont and William Dayton comprised the ticket, which Lincoln supported throughout Illinois. The Democrats nominated former Secretary of State James Buchanan and the Know-Nothings nominated former Whig President Millard Fillmore.