Postmaster General Preston R. Tisch will return to private business sometime in the next few months, he announced yesterday.

No departure date was set, and Tisch said he will remain on the job until the independent agency's board of governors selects a successor. He said he expects to leave "in the spring."

Tisch, 61, postmaster general for 18 months, said he plans to return to business in New York City, where his family owns Loews Corp.

He said he is likely to return to Loews and said he has "some ideas" for development of individual divisions of Loews. He declined to discuss specifics.

As the 68th postmaster general, Tisch took over the troubled agency after a purchasing scandal in which postal and private business officials were jailed.

Tisch applied business principles to the operation, tightening the budget of the agency that did $30 billion in business in 1986. He also renewed an automation program and pushed construction and spending programs for new vehicles.

Many of those moves are stalled by the federal budget-cutting process, which could force the postal service to reduce spending by $1.24 billion over the next 21 months.

While he did not tie his leaving directly to the budget cuts, Tisch said he spent the recent holidays contemplating the agency's future and decided to quit.

The federal budget cuts effectively stall new construction and much purchasing for 1988 and 1989 and will have a major effect on the service's five-year capital program, which would require intensive planning and analysis for the future, Tisch said.

He said he is disappointed about the cuts imposed by Congress and said he hopes that the postal service can be dropped from the federal budget and allowed to return to managing its own affairs, as it did before 1985. Christmas holiday.

Christmas season mail totaled 12.6 billion pieces, 560 million more than in the 1986 holidays. The peak was Dec. 14, when the agency handled 168 million cards and letters, and second highest was the 157 million handled Dec. 21.

AP-BA-01-05 1311EST