The congressman defended his decision to speak at the event in July after criticism from state Democrats.
"I regularly speak to groups across the political spectrum because my constituents deserve access to their congressman,” Mulvaney said, according to The State. “I can’t remember ever turning down an opportunity to speak to a group based on the group’s political ideology.”
The Souther Poverty Law Center describes the John Birch Society as a "conspiracist group exiled by the right a half century ago." The group's intense opposition to communism has led its members to accuse President Dwight Eisenhower of being a communist and to label the civil rights movement as communism, as Mother Jones noted.