Federal officials and lawmakers have agreed to scale down and phase in construction of a proposed $821 million Navy complex in Northern Virginia in an effort to save the massive project from federal budget cuts.

The agreement among the Navy, the General Services Administration and Northern Virginia lawmakers also might limit federal ownership of the facility, in an effort to make the proposal more palatable to local governments.

The compromise is an attempt to breathe life into the Navy proposal, which breezed through the House but received no Senate funding for next year.

The compromise would trim the Navy project, originally envisioned as more than 3 million square feet of federally owned office space for 20,000 workers, to 2 million square feet of space for a Navy staff that is expected to decrease in the early 1990s.

Sen. John W. Warner (R-Va.), ranking Republican on the Senate Armed Services Committee, said that the compromise plan, which would cost $300 million next year and up to $274 million over 1994 and 1995, is "the best plan we could hope for" to try to rescue the project.

Half of the project would be federally owned and built immediately; construction on the other half, which the government would own or lease, would not begin until 1994.

Warner, who was secretary of the Navy during the Nixon administration, has acknowledged that the original plan, conceived during the military buildup of the mid-1980s, is out of date. He is expected to present the compromise plan to a House-Senate conference committee next week.

"Given the fiscal problems we have right now, I just want to get something tied down," Warner said. Trimming the size and cost of the project "might make it a little easier" for lawmakers to accept, he said.

The GSA and the Navy are examining six sites for the project -- three in Arlington, three in Alexandria -- that have been proposed by five developers. The Charles E. Smith Cos., which now leases space in Crystal City for about 16,000 Navy workers who would move to the new complex, submitted two of the proposals.

Congressional sources said that by opening the door for half of the Navy project to be leased by the federal government, federal officials are hoping to gain support among local officials who have been against the project because the U.S. government has planned to own it.

Federally owned land is tax-exempt, and officials in Arlington say a government-owned Navy complex there could cost the county $6 million a year in lost tax revenue. Alexandria officials say the city could lose $5 million a year if the complex were built there.

Arlington and Alexandria officials were lukewarm to the compromise plan yesterday, noting that it still would cost their jurisdictions millions of dollars in annual revenue. They said there still are many issues, such as road improvements and the impact of such a complex on nearby neighborhoods, that need to be examined further.

"It sounds like it's closer, but no cigar," Arlington County Board Chairman Albert C. Eisenberg, a Democrat, said of the new Navy plan. "What we want is the Navy's presence in Arlington in leased space . . . in a situation in which our revenues aren't clobbered."

Eisenberg, who along with other Arlington officials sent a letter to Senate leaders last month urging that funding for the Navy project be withheld, said construction of a federally owned Navy complex could be particularly harmful because of continuing state and federal funding cutbacks.

"What gets me going is that at a time when we're taking hits from the state and federal governments, they're talking about dropping something like this on us," Eisenberg said. The Navy project "can be worked out, but it's going to take good creative thinking and a will to do it. So far I haven't seen much of either."