the people living in the territory could decide the issue when a territorial legislature was convened. Southern Democrats disputed this idea, arguing that the issue of slavery must be decided at the time of adoption of a state constitution, when the request was made to Congress for admission as a state. Cass and other Democratic leaders failed to clarify the issue so that neither section of the country felt slighted as the election approached. After Cass' defeat in 1848, Illinois Senator Stephen Douglas assumed a leading role in the party and became closely associated with popular sovereignty with his proposal of the Kansas–Nebraska Act. California Gold Rush The election of 1848 produced a new President from the Whig Party, Zachary Taylor. President Polk did not seek reelection because he gained all his objectives in his first term and because his health was declining. From the election emerged the Free Soil Party, a group of anti-slavery Democrats who supported Wilmot's Proviso. The creation of the Free Soil Party foreshadowed the collapse of the Second party system; the existing parties could not contain the debate over slavery for much longer. The question of slavery became all the more urgent with the discovery of gold in California in 1848. The next year, there was a massive influx of prospectors and miners looking to strike it rich. Most migrants to California (so-called 'Forty-Niners') abandoned their jobs, homes, and families looking for gold. It also attracted some of the first Chinese Americans to the West Coast of the United States. Most Forty-Niners never found gold but instead settled in the urban center of San Francisco or in the new municipality of Sacramento. Compromise of 1850 The influx of population led to California's application for statehood in 1850. This created a renewal of sectional tension because California's admission into the Union threatened to upset the balance of power in Congress. The imminent admission of Oregon, New Mexico, and Utah also threatened to upset the balance. Many Southerners also realized that the climate of those territories did not lend themselves to the extension of slavery (it was not yet foreseen that the Central Valley in California would someday become a center of cotton farming). Debate raged in Congress until a resolution was found in 1850. President Taylor threatened to personally command an army against any Southern state that would secede from the Union, and he also threatened