Cambridge Mayor Francis H. Duehay 55, a city public servant for 36 years, has announced he will retire from political life when his term ends next January.

"Term limits have finaly reached me," Duehay joked in an interview yesterday.

"When you've had 18 elections, you begin to realize that it would be better to leave when people are saying, ' Isn't it too bad he's leaving,"'he said.

Duehay says the daily grind of policy negotiations and legislative wrangling have finally caught up with him.

"If I stayed another term, I'd be nearly 69 years old," he says. "There are several things I'm interested in doing. But I don't have time to think about that because I'm too busy."

Duehay, who is still uncertain about his future plans, began his political career in 1963 as a member of the Cambridge School Committee. After four terms, he was elected to the City Council in 1971. He has served on the council since then and has also served three terms as mayor.

He has dealt directly with nearly every major dilemma Cambridge has confronted in the past 40 years, from racial unrest and student protest in the 1960s to economic woes and crime waves in the '70s, through the desegregation wars of 1980 and 1981 to the economic renaissance of the late '80s and '90s.

"When I first came to the city council in the early '70s, rent control had just been adopted, but it was being so poorly administered that it was being completely ineffective," he says.

Duehay, who has supported rent control from its inception, worked to improve the system by streamlining city agencies and making available hundreds of thousands of dollars in loans to lowincome families.

After nearly a decade of bureaucratic restructuring, he says,"We reformed the housing board. It's now considered one of the best in the country," he says.

Federal, state and local programs aimed at solving housing problems were placed under one roof with the development of the city's Affordable HousingTrust , which Duehay cites as one of his greatestaccomplishments.

"We brought all those disparate groups together," he says.

Duehay estimates that 1,500 housing units havebeen preserved for low- and middle -incomefamilities following rent control's abolition in1996.

Duehay and others on city council foughttooth-and-nail against the loss of rent controlbut eventually lost the battle.

The end of rent control helped lead tochanging Cambridge. The mayor said his greatestdisappointment is his "failure to dealconstructively with the growing racial and classtensions created largely, but not sloely, by theend of rent control."

"It required greater leadership than any of uswere able to provide," he says.