Abolitionist sentiment was not exclusively religious or moral. The Whig Party became increasingly opposed to slavery because it saw it as inherently against the ideals of capitalism and the free market. Whig leader William H. Seward (later Lincoln's secretary of state) proclaimed there was an "irrepressible conflict" between slavery and free labor, and that slavery had left the South backward and undeveloped. As the Whig Party dissolved in the 1850s, the mantle of abolition fell to its newly formed successor, the Republican Party.