There are still 240 detainees in the Guantanamo Bay camp
The US Senate has said it will reject a White House call for funding to close the Guantanamo Bay detention camp.
The Senate will join the House of Representatives in stripping $80m (£52m) from a war funding bill meant for the camp, at a naval base in Cuba.
Democrats and Republicans argue that there needs to be a better plan for closing the camp where 240 terrorist suspects are still detained.
President Barack Obama has said he wants the camp closed by January 2010.
Democratic leaders say they will reconsider providing the requested funds, once the White House has drawn up more detailed plans.
The funding issue appears to be a hiccup rather than a major setback for Mr Obama, says the BBC's James Coomarasamy in Washington.
The closure deadline was set in Mr Obama's first week of office, but since then growing numbers of the president's own party have become concerned about the release of terrorist suspects into their constituencies.
Most democrats support his commitment to close Guantanamo Bay, but realise that agreeing to fund an ill-prepared process would provide fodder for the Republican opposition.
This is not the first time that the president has got into a politically difficult situation trying to strike a balance between national security and fulfilling his campaign commitments, adds our correspondent.
He revived military trials for some Guantanamo Bay detainees, having previously denounced the Bush-era judicial system.
Mr Obama halted them as one of his first acts on taking office, saying the US was entering a new era of respecting human rights.
Introducing new safeguards for detainees, he said he had supported their use as one avenue to try detainees, and in 2006 had voted in favour of them.
He said he had opposed the tribunals used by George W Bush's administration because they had failed to establish a legitimate legal framework and undermined swift and certain justice.
Under extra safeguards for detainees, there will be:
- a ban on evidence obtained by harsh interrogation
- restrictions on hearsay evidence
- more leeway for detainees to choose their own lawyers