Jeffrey Barker, executive officer for communications, policy and public outreach at the California High-Speed Rail Authority, is leaving the embattled agency.
The move comes as Gov. Jerry Brown, a Democrat, continues to recast the administration. Barker, a Republican, was appointed by Republican Gov. Arnold Schwarzenegger and was an aide to Schwarzenegger before joining the Rail Authority.
Barker said he expects to work through next week.
The state's effort to build a high speed rail system connecting Los Angeles and San Francisco has come under increased scrutiny in recent months, with questions about ridership and cost projections.
Barker's departure follows the resignation from the Rail Authority board of Curt Pringle, the former Assembly speaker and Anaheim mayor.
Barker said in a letter that he is proud of the Rail Authority's work and will continue to advocate for high speed rail.
"I'd always planned to stay at the Authority for a year or a bit more, and so after about two full years, I am leaving the employ of the state to pursue other endeavors - back to my writing and communications strategy roots that have taken a backseat while I served the public in an executive management role at the Authority," Barker said in a letter.