[3][4] In 1998, he became the policy advisor to the Assistant Secretary for Environmental Management at the United States Department of Energy (DOE) in Washington, D.C.

While at the DOE, he developed and implemented a program fostering cooperation between federal, state, local and Native American governments to enhance cleanup activities.

As the 30th Attorney General of New Mexico, King spearheaded the effort to get legislation passed that made it a felony crime to engage in the practice of human trafficking.

[citation needed] On June 3, 2014, King won the New Mexico Democratic primary for governor and was immediately endorsed by his opponents; Alan Webber, Lawrence Rael, Howie Morales and Linda Lopez.

They traveled to countries such as Taiwan, France, Italy, the Netherlands, Slovenia, Romania, Poland and the Czech Republic.