Federalist leaders in Massachusetts arranged for Adams's election to the United States Senate in 1802, but Adams broke with the Federalist Party over foreign policy and was denied re-election. In 1809, President James Madison, a member of the Democratic-Republican Party, appointed Adams as the U.S. ambassador to Russia. Multilingual, Adams held diplomatic posts for the duration of Madison's presidency, and he served as part of the American delegation that negotiated an end to the War of 1812. In 1817, President James Monroe selected Adams as his secretary of state. In that role, Adams negotiated the Adams–Onís Treaty, which provided for the American acquisition of Florida. He also helped formulate the Monroe Doctrine, which became a key tenet of U.S. foreign policy. In 1818, Adams was elected a member of the American Philosophical Society in Philadelphia.