WASHINGTON -- The families of United Airlines Flight 93 cleared a hurdle yesterday when a powerful congressman relented to their request for $5 million to buy the Western Pennsylvania land where the plane went down on Sept. 11, 2001.

For more than a year, White House officials and members of the Pennsylvania delegation have pressured Rep. Charles Taylor, R-N.C., chairman of the House panel that controls spending on Interior and National Park Service programs, to allocate the money for the land purchase.

During yesterday's hearing on the interior and environment spending bill for 2007, Mr. Taylor announced that he would do so, but said he was still concerned about the Flight 93 memorial's estimated $58 million cost when many existing parks and memorials lack the maintenance and operation money they need.

He said the committee would agree to spend "precious federal dollars" on the project if "all parties concerned reach a signed, binding agreement as to its scope and sources of funding." He has told Pennsylvania's congressional delegation that he needs greater assurances from involved private groups that they can attain their $30 million fund-raising goal for the memorial.

"We cannot have an open-ended contract; in other words, 'Start appropriating the money, and we'll tell you what it costs later,' " Mr. Taylor said yesterday.

Private groups supporting the memorial have raised more than $8.6 million from some 4,500 donors. That includes $1.14 million from Universal Pictures, which represented 10 percent of the $11.6 million the studio earned at the box office from last week's opening-weekend receipts of its film about Flight 93.

The park service is seeking a total of $10 million for the land. Part of the money would be used to purchase the 1,355 acres that include the crash site outside of Shanksville, Somerset County, where the plane went down, killing all aboard, after passengers and crew overpowered hijackers trying to steer toward the U.S. Capitol in Washington.

The 1,355 acres are needed for the memorial, a visitors center, parking lots and to provide access to the area off Route 30. The rest of the money would allow the park service to protect an additional 900 acres at the site through scenic easements and partnerships. The federal government has already provided $1 million for memorial planning, and the state has agreed to provide $10 million.

But Mr. Taylor has said he believes that the memorial could eventually cost as much as $100 million, and he is worried that the government will have to pick up extra costs.

Parks budgets are already tight: The spending bill Mr. Taylor's committee approved yesterday includes a $100 million cut to the National Park Service's $2.3 billion current-year budget, a $55 million reduction for the Environmental Protection Agency, a $63 million drop in funding for the U.S. Forest Service and a $55 million cut to U.S. Fish and Wildlife programs.

Mr. Taylor's resistance to setting aside funds for the Flight 93 project had worried White House officials and some in the Pennsylvania delegation -- who were concerned that a failure to put the money in the bill would reflect poorly on the Republican Party in a tough election year.

Rep. Bill Shuster, R-Blair, began the recent push for funds several weeks ago, when he asked House colleagues to sign a letter to Mr. Taylor urging that he let the project go forward. Family members of victims of Flight 93 also contacted lawmakers from their states. "The families came to Capitol Hill last week to persuade members of Congress to include the funding, and that's exactly what they did," Mr. Shuster said yesterday.

Esther Heymann, whose stepdaughter, Elizabeth Wainio, was killed on Flight 93 and who joined the other families in Washington last week, said she was pleased by Mr. Taylor's decision but understood his concerns.

"I really respect his position; I think we should all be concerned," she said. "It's easy for anyone to promise an amount of money, and what we need to push is the follow-through -- all of us."

The $5 million allocation must still be approved by the full House Appropriations Committee and be included in a final House-Senate package before it becomes law.

But at yesterday's hearing, one member of Mr. Taylor's committee, Rep. Ernest Istook Jr., R-Okla., offered words of warning for the Flight 93 memorial advocates. He said he was still trying to get the $2 million the federal government promised as an endowment for the memorial to victims of the 1995 Oklahoma City federal building bombing.

Congress approved $5 million in federal spending for that memorial's permanent endowment, but Mr. Istook said he could not get the money through Mr. Taylor's committee and had to instead secure $3 million for the endowment through an earmark in a transportation bill.

During yesterday's hearing, he told Mr. Taylor he was angry that the committee has so far refused to provide the additional $2 million. He noted that Mr. Taylor demanded a similar signed agreement from parties involved in the Oklahoma City memorial.