D.C. City Administrator Thomas M. Downs won't be moving to a new job after all -- at least not yet.

Downs, a finalist for a major transportation job in Philadelphia that will pay $140,000 a year -- about twice his current salary -- lost out yesterday to a San Francisco transit executive who once worked in the City of Brotherly Love.

"The home-town {candidate} won out," Downs said in his office at the District Building. Downs was reported this week to be one of five finalists for the post of general manager of the Southeastern Pennsylvania Transit Authority. The job went to William Stead, director of San Francisco's Municipal Railway.

"I'm disappointed to a certain extent about the decision in Philadelphia. I am relieved in a small sense about not having to make {the decision to move,}" said Downs, who has been city administrator and deputy mayor for operations in Washington for more than four years -- longer than any previous official to hold the post.

In recent months, Downs has widely been rumored to be searching actively for another job in public administration. Downs said yesterday that he was not seeking out other posts but has been contacted about and has considered a number of jobs. Downs said he was contacted in June about the SEPTA post.

Lewis F. Gould Jr., chairman of the SEPTA board, said yesterday that Downs, a former federal mass transit official, was a "highly, highly qualified candidate" with excellent credentials. Gould said the board chose Stead because of his recent "hands-on" experience in running a transit system. Philadelphia sources said Downs' position was not undermined by numerous reports of municipal corruption in Washington. "He strikes me as a man who is squeaky clean," said Gould.

Some aides to Mayor Marion Barry have suggested that Downs' effectiveness could be undercut by department heads who believe Downs is actively trying to leave the city government. Downs disputed suggestions from friends that he is "burned out" by a series of problems that have troubled the Barry administration, including ongoing federal probes of city contracting procedures.

"I've been doing this in public life for 20 years. This is what I do," Downs said. "If I didn't like {public service} I wouldn't do it." Downs said he has planned all along to move from his current city administrator's post to some type of hands-on position in public transportation.

The SEPTA job involves overseeing the daily operations of a $544 million transit system with about 9,000 employes -- far smaller than the $3 billion city budget of the District, which employs about 40,000 persons. However, the transit post would be a return to his primary interest: transportation.

Downs, formerly executive director of the federal Urban Mass Transportation Administration, began work in the District as director of the city's old transportation department. He moved up to director of public works for all city services and was named city administrator in May 1983.