PHILADELPHIA — Relatives of those who died aboard United Airlines Flight 93 want the Bush Administration to seize the land needed for a memorial where the plane crashed during the 9/11 terrorist attacks.

The Families of Flight 93 sent a letter earlier this month asking President George W. Bush to empower the Secretary of the Interior to take the land in dispute from a homeowner who had been in negotiations with the National Park Service, said Patrick White, vice president of the families' organization.

The group says ground must be broken early next year in Shanksville for a memorial to be built for the 10th anniversary of the crash in 2011.

Svonavec Inc. owns one of the last large chunks of land needed for the 2,200-acre memorial, including the area where the plane crashed Sept. 11, 2001. Svonavec's treasurer Mike Svonavec has said the park service has not done enough to negotiate a deal. He did not immediately return a call for comment on Sunday.

White said Svonavec has not been willing to negotiate, and called that unacceptable.

"We've certainly sought to do this within in the process, following protocol as much as we possibly can," White said Saturday. "It has gotten to the point where we fear we'll lose significant momentum.

"We have an administration that has been very supportive of this effort. We just wanted to make sure the president is aware of what the circumstances are. "

The White House said it was reviewing the letter.

"The president recognizes the contributions of those working to memorialize the heroes of Flight 93 with a fitting tribute at the spot where they gave their lives to ensure that others would live," Pete Seat, a spokesman for the White House, said Sunday.

Bush signed legislation authorizing the building of a national memorial to the passengers and crew of Flight 93 on Sept. 24, 2002. The president has twice visited Shanksville to mourn with those who lost loved ones.

In October, the National Park Service said it would use an independent appraiser to determine the value of 275 acres needed for the memorial. The NPS also said it could use eminent domain to acquire the plot. Construction of a $58 million permanent memorial and national park is scheduled to begin in 2009.

White, whose cousin Louis Nacke II died on Flight 93, said the group would favor Bush giving the interior secretary or director of park services the power to take the necessary steps to acquire the land before the administration leaves office in January.