A District telecommunications official said yesterday that City Administrator Thomas Downs is seeking to fire him because he has opposed efforts to award up to $20 million in telephone contracts to the Chesapeake and Potomac Telephone Co.

Thomas J. Mattingly, a communications specialist with the D.C. Department of Administrative Services, the agency responsible for telephone and other contracts, said he is being ousted at the behest of Delano Lewis, C&P's executive vice president and a longtime supporter of Mayor Marion Barry -- claims that Downs strongly denies.

Mattingly charged that Downs tried to get Jose Gutierrez fired as director of the department because Gutierrez also opposed C&P.

Gutierrez told The Washington Post Friday that he believes he was reassigned to another city position because he resisted pressure from Downs to approve several controversial contracts.

"Tom Downs tried to get Jose Gutierrez fired, and the mayor stopped him," Mattingly said yesterday.

"He has now requested that Bill Johnson [who replaced Gutierrez]in the department terminate my contract," he said.

Downs said yesterday that it is "categorically untrue" that he is trying to force out Mattingly or Gutierrez as part of an effort to steer the telephone contracts to C&P.

He said he does not know whether there is an effort to dismiss Mattingly, and he said that any decision will be made by William Johnson, Gutierrez's successor as director of administrative services.

Johnson could not be reached for comment yesterday.

"I know there is some question raised about the propriety of some of Mr. Mattingly's actions" in the department, Downs said. ". . . There is some kind of deep problem between Mattingly and C&P that I don't understand."

Lewis, in a brief interview yesterday, before Mattingly made his allegations, disputed Gutierrez's claim that the company was exerting political pressure to obtain major contracts to provide telephone service to the District government.

"I don't agree there's political pressure at all," said Lewis, who was a high-ranking official of Barry's 1978 and 1982 mayoral campaigns.

"We've been trying to make our case for the municipal center contract" on merit alone, he said.

"That's all I'm ever about -- that's it," he said. Lewis could not be reached for comment after Mattingly made his charges.

Lewis, sensitive to the growing controversy around C&P's lobbying for city contracts, said that he may soon publicly spell out his company's views on telecommunications issues.

Barry, who said that the controversy surrounding Gutierrez's transfer and the contracts is "making a mountain out of a molehill," declined yesterday to say whether Gutierrez's job with the city has been jeopardized by going public with his concerns.

"You'll be the first to know," Barry quipped when a reporter asked whether he planned to fire Gutierrez.

Mattingly's statements added fuel to a growing controversy over whether Barry's administration was seeking to award contracts on the basis of politics.

On Friday, Gutierrez became the first high-ranking mayoral aide to break rank and allege that Downs was exerting pressure on him to award contracts.

Mattingly, a lawyer who owned a small telephone company here for five years, said Gutierrez hired him as a consultant last October to assist in choosing a new telephone system for the District, including the new municipal office building at 14th and U streets NW, and another for a "911" emergency telephone system.

He said that Downs blocked efforts to hire him full time after he began to question the merits of C&P's proposals for the various telephone contracts.

Mattingly said Downs delayed action on a request by Gutierrez to extend his consulting contract by one year and disapproved it after Gutierrez was transferred to the Office of Policy and Program Evaluation.

Mattingly said he has informally learned that a letter has been drafted terminating his work effective this past Friday.

The debate over the telephone contracts revolves around complex technical issues concerning the merits of the system offered by C&P, known as Centrex, as compared to a telecommunications switching system called PBX, which is being offered by competitors.

Mattingly said he has argued that a digital PBX system will be more versatile and cheaper in the long run than the current C&P Centrex system.

Mattingly said that Barry's assertion that residential phone rates might rise, to the detriment of low-income families and the elderly, if C&P loses out on the contracts "is patently false."

In effect, residential rates already are subsidizing the Centrex service C&P provides the city and other large customers, according to Mattingly, and C&P currently is seeking a major residential rate increase.

A government source familiar with the issues said yesterday that Mattingly "knows his stuff."

"Sometimes he rubs people the wrong way," the source said yesterday. "But the bottom line is he knows his stuff and is making it difficult for people to do what they want to do."