Led by John Van Buren, the Barnburners bolted from the 1848 Democratic National Convention after the party nominated a ticket consisting of Senator Lewis Cass of Michigan and former Congressman William O. Butler of Kentucky; Cass and Butler had both opposed the Wilmot Proviso. Shortly after the Democrats nominated Cass, a group of Whigs made plans for a convention of anti-slavery politicians and activists in the event that the 1848 Whig National Convention nominated General Zachary Taylor of Louisiana for president. With the strong backing of slave state delegates, Taylor defeated Henry Clay to win the Whig presidential nomination. For vice president, the Whigs nominated Millard Fillmore of New York, a conservative Northerner. The nomination of Taylor, a slaveholder without any history in the Whig Party, spurred anti-slavery Whigs to go through with their convention, which would meet in Buffalo, New York in August. A faction of the Liberty Party led by Salmon P. Chase agreed to attend the convention, though another faction of the party, led by Gerrit Smith, refused to consider merging with another party.