After returning to the United States, Adams established a successful legal practice in Boston. In 1794, President George Washington appointed Adams as the U.S. ambassador to the Netherlands, and Adams would serve in high-ranking diplomatic posts until 1801, when Thomas Jefferson took office as president. 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, Adams was appointed as the U.S. ambassador to Russia by President James Madison, a member of the Democratic-Republican Party. He also helped formulate the Monroe Doctrine, which became a key tenet of U.S. foreign policy. 8.2 Memorials. While his predecessors had engaged in projects like the building of the National Road, Adams promised that he would ask Congress to authorize many more such projects.