The new Department of Homeland Security headquarters in Northwest Washington gives the fledgling Cabinet agency tight security and ample room to grow, features that may factor into any future search for a permanent home, officials said yesterday.

As the department began talks with the Navy to occupy several buildings at the Naval District of Washington's 38-acre Nebraska Avenue complex, Virginia lawmakers quietly fumed and District leaders and their Democratic supporters in the House took some credit for the location choice.

Though city officials and neighborhood leaders worried over the impact on traffic and parking, they welcomed the surprise decision to base the government's third-largest department in the District with a jolt of civic pride, pleased at beating out the competition from Northern Virginia, for now.

D.C. Council member Kathy Patterson (D-Ward 3), who represents the largely affluent residential area around the station, said, "For the District of Columbia, it's a good thing to have federal agencies here where they belong."

But officials at American University, which houses 13,000 students and employees on 84 acres across Ward Circle from the station and wrestles regularly with active neighborhood groups, declined to comment. Residents sounded a be-careful-what-you-wish-for note.

"On a certain level, we were really hoping this agency would stay in the District," said Paul D. Strauss (D), the District's shadow senator and the area's former Advisory Neighborhood Commission representative. "But I'll admit this is not what we expected."

As the base sealed off media access yesterday and prepared for the first of about 100 staff members to begin moving in Monday, Ridge's office expanded on its reasons for choosing the base over a Northern Virginia office building, as recommended by the General Services Administration after a two-month search.

A letter dated Wednesday from the department's transition chief of staff, Bruce M. Lawlor, to GSA Administrator Stephen A. Perry said the government's real estate arm did not treat security as the highest priority when it recommended a suburban site outside the commercial no-fly zone over Washington.

Ridge spokesman Gordon Johndroe brushed off criticism from Capitol Hill and the GSA that the department's security requirements had changed as late as Wednesday. Johndroe said other advantages at the Washington site include operational readiness, proximity to Washington decision makers and cost. Homeland Security was prepared to spend up to $250 million for a 10-year lease in Northern Virginia. Johndroe said the lease costs at the D.C. site were not immediately available.

Virginia lawmakers grumbled that both Homeland Security and GSA would face a changed "political dynamic" from their members, who spearheaded the Bush administration's effort to push a controversial lease approval through the Congress this month on assurances that Northern Virginia was the choice.

Instead, two hours after the Senate confirmed Ridge's nomination as secretary, several Virginia congressional officials said, a junior aide was dispatched to say that the highly sought-after deal was dead.

Capitol Hill sources said they were told by GSA that Ridge rejected the Virginia site after inspecting it Sunday. Johndroe said that multiple people were involved in the decision.

Del. Eleanor Holmes Norton (D-D.C.) praised Ridge and the White House for "keeping an open mind," adding, "The location of the department here greatly enhances the District's chances for the location of the permanent headquarters."

Norton and Democratic leaders of the House panel that oversees the GSA wrote to Perry, and Mayor Anthony A. Williams (D) wrote to President Bush. The letters urged reconsidering a move to Northern Virginia, citing in part the cost to taxpayers of a commercial lease.

In the end, the selection of the Nebraska Avenue complex, which already houses a $14 million homeland security command center, opens a new chapter for a Navy base that was home to the Mount Vernon Seminary before it was commandered by the government in 1942.

The site, which is served by six Metro bus lines and two nearby Metro rail stations, is an electronics warfare center that at its peak during the Cold War occupied 32 buildings and housed more than 2,300 workers. About 1,100 people are employed at the site, which is shrinking through redeployments.

The Navy has said the site contains about 566,000 square feet of office space. Homeland Security will flesh out the headquarters' size and moving timetable over a five-week transition period.

Staff writer Craig Timberg and news researchers Mary Lou White and Lucy Shackelford contributed to this report.