A Maine psychiatrist has taken the helm as executive director of the advocacy group Physicians for Social Responsibility.

Dr. Peter Wilk, 58, took over Monday as executive director of the national organization, which has more than 30,000 members. He said he plans to work with Congress and the new administration to reduce the threat of nuclear weapons and to fight global climate change.

Wilk has been a leader of the group’s state chapter for the past 26 years and is known as an activist for peace, environmental protection and an end to gun violence.