The White House says Bush has already decided to close the U.S. prison in Cuba and transfer more than 370 terrorism suspects elsewhere, possibly including the maximum-security military prison in Fort Leavenworth, Kan.
The 5-year-old prison has become a focus for criticism of the Bush administration at home and abroad. Only a few detainees have been selected for trial, leaving the majority in legal limbo and barred from protesting their detentions in court.
With no timetable announced by Bush, Congress is moving ahead on its own. Acting before Bush is ready would enable Democrats to claim victory in closing the prison.
"What I'm most concerned about is that we uphold a rule of law and not give our enemies a compelling talking point that we are not true to our principles," said Rep. Jim Moran, D-Va. "As long as we detain people indefinitely without charging them, it's a potent weapon in the propaganda war against this country. And that's what Guantanamo has become."
Guantanamo's annual operation budget is about $125 million a year.
Moran said cutting the budget by half would keep the prison afloat for part of the year, giving the administration time to transfer the detainees. Moran wanted to force an immediate shutdown but said there was concern among other lawmakers that doing so would put in question the secure detention of the prison's most dangerous inmates.
"If we allow it to stay open for half the year, it's all the more difficult for the administration to object," said Moran.
Defense Secretary Robert Gates said Friday the administration wants to close the prison and is working hard to find a suitable alternative, but he didn't say how much progress was being made.
The challenge is finding the legal basis to hold indefinitely suspects "who should never be released and who may or may not be able to be put on trial," Gates told a Pentagon news conference.
Rep. David Obey, D-Wis., who chairs the House Appropriations Committee, declined to confirm details of the House funding proposal. But he said, "Do I think it should be closed? Damn right I do."
Moran, a member of the panel's subcommittee that oversees military funding, said the 2008 spending bill is the Democrats' first real chance to force the closure of Guantanamo since taking control of Congress in January. A 2007 war spending bill considered earlier this year did not include enough money specifically for Guantanamo to force its closure and there was still much political opposition to the plan, he said.
Despite Bush's stated intention to shut the facility on his own, the House bill is likely to attract much opposition from Republicans and possibly even some Democrats. In May, the House voted narrowly — 220 to 208 — on a much milder proposal by Moran demanding that Gates devise a plan to transfer detainees out of Guantanamo. Opposing the legislation were 15 Democrats.
In a June letter to the president, Rep. Duncan Hunter said any plans to close Guantanamo were "misguided" and "dangerous."
"Once these detainees are brought onto U.S. soil, the detainees may acquire minimal rights under the Constitution," including the right to protest their detentions in court, said Hunter of California, the top Republican on the Armed Services Committee. "This change in status will inevitably spawn a completely new round of litigation."
Moran said he thinks he has the support to push the proposal through. In a letter to Bush released Friday, more than 140 House members joined him in calling for the facility's closure and said detainees should be allowed to protest their detentions in federal courts through habeas corpus petitions.
The Supreme Court announced the same day it planned to consider whether detainees should be allowed to use the civilian court system. Bush contends that the law allows a president to hold enemy combatants until the war ends.
The lawmakers wrote to him, "Holding prisoners for an indefinite period of time without charging them with a crime goes against our values, ideals and principles as a nation governed by the rule of law."