Smith has been a supporter of the Green Party and backed Ralph Nader in the 2000 United States presidential election. She led the crowd singing "Over the Rainbow" and "People Have the Power" at the campaign's rallies, and also performed at several of Nader's subsequent "Democracy Rising" events.
Smith was a speaker and singer at the first protests against the Iraq War organized by Louis Posner of Voter March on September 12, 2002, as U.S. President George W. Bush spoke to the United Nations General Assembly. Smith supported Democratic candidate John Kerry in the 2004 election. Bruce Springsteen continued performing her "People Have the Power" at Vote for Change campaign events. In the winter of 2004/2005, Smith toured again with Nader in a series of rallies against the Iraq War and call for the impeachment of George W. Bush.