Chesapeake & Potomac Telephone Co. and the union that represents 32,000 company employees reached a tentative contract agreement yesterday, reducing to two the number of labor contracts that must be settled to end the nationwide strike against American Telephone & Telegraph Co.

A spokeswoman for the 525,000-member Communications Workers of America said the C&P workers would continue the 21-day-old nationwide walkout along with other union members across the country until-agreements are reached with Bell Telephone of Pennsylvania and Western Electric's installation division.

The spokeswoman said that "there has been some movement . . . some slight indication of progress" in those talks.

"We are hopeful we can conclude those satisfactorily, just as we did" in the C&P bargaining, she said. C&P provides telephone service in the District, Maryland, Virginia and West Virginia.

Wages, benefits and other major issues had been resolved in national contract talks, which concluded last Sunday. However, negotiations between CWA locals and several of AT&T's 34 subsidiaries continued past a midnight Wednesday deadline.

Union officials have accused the subsidiaries of prolonging the bargaining with proposals to reassign workers and change job descriptions and pay grades. The union characterized some of these proposals as "take-back demands," last-minute attempts to undermine previous union gains.

Last night, a union official praised the new agreement with C&P and asserted that the company had dropped the so-called "take-backs."

"We got rid of all that," during the past few days' bargaining at the Sheraton-Washington Hotel, said George Strick, a CWA vice president. "I feel very good about it," he said of the agreement reached yesterday afternoon.

Mike Houghton, a C&P spokesman, termed the so-called "takebacks" as "not an issue for us" and said the company is "not trying to take back anything.

"Our primary concern is that we've got a local agreement," he said. The spokesman said the utility is "very pleased" with the settlement, which affects telephone operators, repair workers, installers, central office employes and others.

Union officials said ratification votes on both the national and local agreements would be held only after all the AT&T labor agreements have been concluded.

AT&T has also responded to the union's charge of attempts at "takebacks" in the local bargaining saying that its subsidiaries "have been bargaining responsibly since May 19."

Tensions inherent in labor negotiations apparently were exacerbated in the telphone company talks on both the local and national level this year by the impending breakup of AT&T.

Under a court-approved divestiture, AT&T will sever its ties with the regional operating companies which will be reformed into seven independent operating organizations.

When the existing operating companies are merged and consolidated into seven new companies, an undetermined number of worker positions are expected to be eliminated on grounds that they are duplicative.

In addition to job security, the union described pay as a second major issue during national bargaining. Under the tentative national settlement, the average hourly wage for telephone workers would rise from $12.33 an hour to $14.35 at the end of the contract in 1986.

Yesterday's local agreement, according to Strick, would improve the pay scale for employes in the smaller towns, where wages are traditionally lowest, and will also increase the premium pay for certain employes on evening and night shifts.

While CWA workers remained on strike yesterday, a union official said union members were ordered back on the job in three Texas communities where tentative agreement has been reached. CWA members in Houston, Galveston and Texas City were ordered back because of still-uncleared damage from Hurricane Alicia and the possibility of yet another storm, union president Glenn E. Watts said.