As mayor, Anderson rose to nationwide prominence as a champion of several national and international causes, including climate protection, immigration reform, restorative criminal justice, LGBT rights, and an end to the "War on Drugs". Before and after the U.S. invasion of Iraq in 2003, Anderson was a leading opponent of the invasion and occupation. Anderson was the only mayor of a major U.S. city who advocated for the impeachment of President George W. Bush, which he did in many venues throughout the United States.