President Barack Obama's campaign pledge to shut the prison at Guantánamo Bay was rejected by his own party yesterday when Senate Democrats joined their Republican counterparts in voting not to pay for the closure.

The vote is the latest setback for the Obama administration, which has been widely criticised by supporters for deciding to restart the controversial military tribunals for detainees, first established by President George Bush, but halted by Obama when he came to office.

The 90-6 vote in the Senate follows a similar decision in the House of Representatives last week - a clear sign to Obama that he may struggle to convince the Democratic-controlled Congress to agree with his plans to shut down the detention centre and move the 240 detainees.

Last month, Obama asked for $80m (£60m) for the Pentagon and the US justice department to close the facility at Guantánamo Bay, Cuba, by January. The administration put its congressional Democratic allies in a difficult spot by requesting the Guantánamo closure money before developing a plan for what to do with its detainees.

Obama is scheduled to give a major address tomorrow outlining in more detail his plans for Guantánamo, but it's already clear that Congress has little appetite for bringing detainees to US soil, even if the inmates would be held in maximum-security prisons.

Harry Reid, the Democratic leader in the Senate, said that none of Guantánamo's detainees should be transferred to the US to stand trial or serve time in prison. "We don't want them around," he said. "I can't make it any more clear … We will never allow terrorists to be released in the United States."

The vote came as FBI director Robert Mueller told Congress that he is concerned Guantánamo detainees could support terrorism if sent to the US. Separately, a federal judge said the US can continue to hold some prisoners at Guantánamo indefinitely without any charges.

"The concerns we have about individuals who may support terrorism being in the United States run from concerns about providing financing, radicalising others," Mueller said, as well as "the potential for individuals undertaking attacks in the United States".

In recent weeks, Republicans have called for keeping Guantánamo open, saying abuses at the facility are a thing of the past and describing it as a state-of-the-art prison that's nicer than some US prisons. And they warn that terrorists who can't be convicted might be set free in the United States.

"The American people don't want these men walking the streets of America's neighbourhoods," Senator John Thune, a Republican, said today. "The American people don't want these detainees held at a military base or federal prison in their backyard, either."

But Obama's new Pentagon policy chief, Michele Flournoy, said it is unrealistic to think that no detainees will come to the US, and that the government can't ask allies to take detainees while refusing to take on the same burden.

Obama ally Senator Dick Durbin, a Democrat, pointed out that not a single prisoner has ever escaped from a federal super maximum security prison and that 347 convicted terrorists are already being held in US prisons.

Senator Lindsey Graham of South Carolina, among the few Republicans joining former GOP presidential nominee John McCain of Arizona in calling for Guantánamo to be closed, scoffed at the idea that the government can't find a way to hold Guantánamo prisoners in the United States. Graham noted that 400,000 German and Japanese prisoners were held during the second world war.

"The idea that we cannot find a place to securely house 250-plus detainees within the United States is not rational. We have done this before," Graham said. "But it is my belief that you need a plan before you close Gitmo."

While allies such as Durbin have cast the development as a delay of only a few months, other Democrats have made it plain they do not want any of Guantánamo's detainees sent to the US to stand trial or serve prison sentences.