Who spoke out against adding land in the Southwest to the United States?

Ralph Waldo Emerson spoke out against the expansion of U.S. territory into the Southwest, criticizing the Mexican-American War and the effort to acquire more land. James Polk supported expansion as president, while James Slidell and Winfield Scott were involved in the war and its diplomacy. The correct choice is Ralph Waldo Emerson.

AI-written and checked against the verified answer.