In 2008, Sullivan was an advisor to Hillary Clinton during the primary cycle and then to Barack Obama during the general election campaign. He prepared Clinton and Obama for debates. When Clinton became secretary of state, Sullivan joined as her deputy chief of staff and
director of policy planning, and he travelled with her to 112 countries.
Sullivan worked in the Obama administration as deputy assistant to the president and
national security advisor to
Vice President Joe Biden. He became Biden's top security aide in February 2013 after Clinton stepped down as secretary of state. In those posts, he played a role in shaping U.S. foreign policy towards
Libya,
Syria, and
Myanmar.
