Mayor Ted Wheeler's chief of staff, Maurice Henderson, is leaving to become the chief operating officer of TriMet.

Henderson had been chief of staff since the mayor took office a year and a half ago.

An email Wheeler sent to City Hall staff did not say who will replace Henderson.

"Maurice has been a trusted friend and advisor on behalf of my administration," Wheeler writes in the email. "The city is fortunate to have had him serve with us for the past 3.5 years."

Prior to Wheeler's taking office, Henderson served as an assistant director of the Portland Bureau of Transportation beginning in 2015. He came to Portland from Washington, D.C. where he served in three mayoral administrations and also as spokesman for U.S. Sen. Tim Kaine (D-Va.) when Kaine was governor of Virginia.