Throughout the 1840s he contributed freelance fiction and poetry to various periodicals, including "Brother Jonathan" magazine edited by John Neal. Whitman lost his position at the "Brooklyn Eagle" in 1848 after siding with the free-soil "Barnburner" wing of the Democratic party against the newspaper's owner, Isaac Van Anden, who belonged to the conservative, or "Hunker", wing of the party. Whitman was a delegate to the 1848 founding convention of the Free Soil Party, which was concerned about the threat slavery would pose to free white labor and northern businessmen moving into the newly colonised western territories. Abolitionist William Lloyd Garrison derided the party philosophy as "white manism".