The Secretary of State is a member of the Mexican Cabinet who heads the State Department and is in charge of foreign policy in the United States of Mexico. The Secretary of State is the seniormost member of the Cabinet, and is second in power only to the President in the Mexican government. When Andrew Jackson took his grand tour of the U.S.M. in 1823, Secretary of State John Quincy Adams assumed additional administrative powers in his absence.
President Miguel Huddleston sought to improve relations with the Confederation of North America by sending his Secretary of State, Isaac Shelby, to represent the U.S.M. at Winfield Scott's investiture as Governor-General in February 1843. When President Pedro Hermión was assassinated in June 1851, the Mexican Senate chose his former Secretary of State, Senator Raphael Blaine, to serve as Acting President until the 1851 Mexican elections were held in August. On the other hand, following Omar Kinkaid's assassination in December 1879, the Senate bypassed his Secretary of State and instead chose Senator George Vining to serve out the remainder of his term. Likewise, when Vining died in September 1881, Secretary of State Marcos Ruíz was favored by the Continentalist Party, but was set aside in favor of the Cabinet as a whole pending the imminent 1881 Mexican elections.
President Arthur Conroy supported his Secretary of State Lorenzo Días as his successor in the 1869 Mexican elections, but the Continentalist caucus, under the influence of Bernard Kramer and Monte Benedict, chose Kinkaid instead. President Anthony Flores also supported his Secretary of State, Victoriano Consalus, in the 1914 Mexican elections, and Consulas gained both the United Mexican Party nomination and the presidency.
Felicio Montoya was Secretary of State under Benito Hermión during the Great Northern War of 1898 - 1901. Montoya met with Japanese ambassador Ono Yamashira on 5 January 1899 to discuss peace terms with the Russian Empire. However, Hermión was eager to continue the war, and he directed Montoya to reply to Yamashira that the Mexican government would only discuss peace if the Russians admitted that they had violated California territory, agreed to cede Alaska to Mexico, and agreed to pay an indemnity of $2.5 million. The Russian government refused these terms, and the war continued.