Builders and developers won a reprieve this week when a divided D.C. Zoning Commission postponed a vote on a proposal that would require them to provide housing on downtown sites where they would prefer to build office buildings.

But developers who oppose the plan and community activists who support it agree that the commission seems determined to demand some downtown housing. The main questions are how much housing the commission will require, and whether it will give developers any economic incentives to soften the blow, they said.

"It's pretty clear the housing . . . will go forward in some form," said Patricia A. McGrath, publisher of The D.C. Zoning News, a newsletter for developers. "Maybe there's a little bit of hope that there'll be a little bit of tempering, a little bit of flexibility" in the regulations the commission ultimately adopts, McGrath said.

Since late last year the commission, made up of three mayoral appointees and two federal government representatives, has grappled with proposals that could affect the fortunes of already beleaguered commercial developers and the shape of downtown Washington's East End for generations.

The outcome of these deliberations also could determine how much money downtown developers contribute for subsidized housing in other parts of the District.

The commission has decided to accept additional public comment for the next 45 days and hopes to make a decision by mid-September. The commission is also considering hiring a consultant to advise it on the matter.

Advocates of downtown housing said Washington needs a larger residential population in the heart of the city if it is to become one of the great cities of the world. They said housing will make downtown a safer and more appealing place for businesses.

Developers, alarmed by the financial implications of the proposal, said they should be allowed to build offices on their expensive downtown land and subsidize housing in other parts of the city, where their money would produce more housing.

Leaders of the D.C. Downtown Partnership, an alliance of business, government and civic officials, called on the Zoning Commission to put off a decision.

In a letter to the commission last week, D.C. Council Chairman David A. Clarke, a Democratic candidate for mayor, said the plan the commission was considering "poses the real risk of cutting off the engine of economic development in the city, further curtailing commercial and residential development downtown and producing little if any affordable housing anywhere."

That letter and many others arrived after the commission had stopped accepting public comments.

The debate Monday night suggested that the commission members' stands on the housing question relate to where they sit professionally.

The strongest advocates on the panel for downtown housing are Commission Chairman Tersh Boasberg, appointed by Mayor Marion Barry, and John G. Parsons, who represents the National Park Service.

Boasberg is a historic preservation lawyer who successfully lobbied to block development of a shopping mall on the Manassas Civil War battlefield. He has fought to shelter Northwest Washington neighborhoods from commercial development.

Parsons has worked with the Pennsylvania Avenue Development Corp., a federal agency, to create housing along Pennsylvania Avenue, and he has said he wants to see the Pennsylvania Avenue housing buttressed by other residential development.

Commission members Lloyd Smith and Maybelle T. Bennett, who are both mayoral appointees, bring a different perspective to the debate. They urged the commission to postpone a decision until it learned more about the economic implications of a housing requirement.

Smith is executive director of the Marshall Heights Community Development Corp., which builds housing for low-income people in the Marshall Heights neighborhood in Southeast. The community development group is part of a coalition of nonprofit housing developers that has waged an emotional campaign against the downtown housing requirements.

If commercial developers are given the option of subsidizing housing instead of building it downtown, the subsidies would help nonprofit builders like the Marshall Heights group do their work. Bennett is research director for the Coalition on Human Needs, a lobby that deals with welfare and similar issues.

Bennett said she ideally would want commercial developers to fulfill their entire housing quota by subsidizing housing outside the downtown area, but added that she is open to a compromise.

Some observers view William Ensign, who represents the Architect of the Capitol, a congressional office, as a potentially pivotal vote. Ensign has said he would support a downtown housing requirement with a provision that developers could fulfill a quarter of their housing quota through subsidies, but he has been less insistent in his public comments than Parsons or Boasberg.