Parker graduated Phi Beta Kappa from Williams College in 1965 and went on to receive his MDiv from Union Theological Seminary of Columbia University.

Parker served as an ordained Protestant minister in UCC churches in East St. Johnsbury and Lower Waterford (1968-1989).

After serving in the Senate, Parker went on to become the Director of the Energy Efficiency Division of the Vermont Department of Public Service (1990-2003).

In the summer of 2006, his campaign staff tripled in number, bringing on full-time field, finance, and communications directors, as well as several support staffers.

The Parker campaign focused on several issues, including energy, education, health care, and economic development.