With mix of Democratic, Whig, and Liberty Party attendees, the National Free Soil Convention convened in Buffalo early August. Anti-slavery leaders made up a majority of the attendees, but the convention also attracted some Democrats and Whigs who were indifferent on the issue of slavery but disliked the nominee of their respective party. Salmon Chase, Preston King, and Benjamin Franklin Butler led the drafting of a platform that not only endorsed the Wilmot Proviso but also called for the abolition of slavery in Washington, D.C. and all U.S. territories. With the backing of most Democratic delegates, about half of the Whig delegates, and a small number of Liberty Party leaders, Van Buren defeated John P. Hale to win the fledgling party's presidential nomination. For vice president, the Free Soil Party nominated Charles Francis Adams Sr., the youngest son of the recently-deceased John Quincy Adams.