POLK DOCTRINE. In 1844, James K. Polk, the Democratic candidate for the U.S. presidency, campaigned on expansionism, reaffirming the Monroe Doctrine and advocating "reoccupying" Oregon and "reannexing" Texas. He also set out to acquire California. As president, in his first annual message to Congress in December 1845, he declared the United States opposed to "any European interference" in the Americas, even "by voluntary transfer." In 1848, Polk reinforced that view to prevent Yucatán from seceding from Mexico and joining a European nation. Latin American nations viewed the Polk Doctrine as encroaching on their sovereignty, but Polk defended it, claiming the United States would prevent European domination of weak American nations.
Mahin, Dean B. Olive Branch and Sword: The United States and Mexico, 1845–1848. Jefferson, N.C.: McFarland, 1997.