In 1990, Sykes became one of the founders of the Green Party of Alaska. As a result, Sykes initiated a lawsuit, Sykes v. Alaska, relying heavily upon case law established in the earlier ballot access lawsuits of Joe Vogler during the 1970s and 1980s. The lawsuit allowed the Green Party onto the ballot in similar fashion to the original ballot access status of the Alaskan Independence Party prior to its becoming a recognized political party. This lawsuit also led to the lessening of the threshold needed to become recognized as a political party in Alaska. In the 1990 gubernatorial election, Sykes ran as the Green Party nominee and garnered 3.3% of the vote. This established Alaska as the first state to obtain ballot access for the Green Party in the United States.
Sykes continued to be active in Green Party politics, running for the U.S. Senate in twice in 2002 and 2004. He received 7.24% of the vote in 2002  and 2.22% in 2004.