John Slidell, a Democratic congressman from Louisiana, was sent to Mexico by President James K. Polk in November 1845 to secure a boundary adjustment between the United States and Mexico. Polk authorized Slidell to offer Mexico up to $50 million for its vast northern territories. The mission failed when the Mexican government refused to accept his credentials. The United States declared war on Mexico on May 13, 1846, and Slidell returned in January 1847 and resigned.
