King County Executive Elect Dow Constantine announced today that his former primary rival, State Sen. Fred Jarrett (D-Mercer Island), has agreed to join his administration as Deputy Executive, the highest ranking staff position in the incoming administration.

Citing his experience as both a respected legislator and retired Boeing executive, Constantine said his background in both the public and private sector made Jarrett a good match for the demands of the Deputy seat.

“Fred’s willingness to assume this leadership role will assure that the ideas he and I shared on the campaign trail, and those generated by our large, diverse transition team, will be carried forward at the County,” Constantine said. “I cannot think of a more perfect fit to address the challenges and opportunities that we face while we remain true to our core values.”

The Deputy Executive position is expected to be enhanced with additional responsibilities compared to previous county leadership, making Jarrett a “clear second in command” as the “(King) County’s Chief Operating Officer.”

Jarrett, currently one of the co-chairs of the Constantine transition committee, said he was honored to accept the leadership role, but wasn’t sure when he could actually start work in Seattle when the new executive takes over on Nov. 24.

He said he will give up his legislative seat before the beginning of the next legislative session begins in Olympia, scheduled for the second week of January 2010.

He compared the decision to accept the offer as a thrill similar to the experience of jumping from a 40-story building — without mentioning how he’d actually survive it.

“I am excited and feeling the rush of air go by,” he said.

“The sheer terror hasn’t hit yet.”

Jarrett will be replaced temporarily by appointment made by the King County Council, based on a list preferred candidates drawn up by 41st Legislative District Democratic Party officers. He served four terms in the state House of Representatives as a Republican representing the Eastside’s 41st Legislative District, but switched to the Democratic Party before he was elected to the Senate seat in 2008. The senate seat will ultimately be up for re-election for the remainder of the term in Nov. 2010.

His district includes south and central Bellevue, Mercer Island, Newcastle and parts of Renton and Issaquah.

Constantine’s office also recognized Jarrett’s wide-ranging policy ideas and what they called his inclusive, non-partisan approach to leadership. In the state Senate, he served as vice-chairman of the Higher Education and Workforce Development Committee and also served on the Transportation and the Early Learning and K-12 Education Committees.

Jarrett retired from Boing after 35 years and is a former Mercer Island Mayor, City Council and school board member. He graduated from Mercer Island High School and continues to live on Mercer Island with his wife Susan.

Other key appointments to the new administration will reportedly be announced in upcoming days.