The Senate is poised to pass the Commerce, Justice and science appropriations bill this week, but not before debating how to handle the criminal trials of alleged 9/11 conspirators.

An amendment by Sen. Lindsey Graham (R-S.C.) would block individuals involved in the Sept. 11, 2001, terrorist attacks from being tried in U.S. civilian courts and instead require them to go before military commissions. Graham released a letter Thursday from 150 family members of victims of the terrorist attacks supporting the amendment, which could receive a floor vote.

“We adamantly oppose prosecuting the 9/11 conspirators in Article III courts, which would provide them with the very rights that may make it possible for them to escape the justice which they so richly deserve,— the letter states.

The letter added, “The public has a right to know that prosecuting the 9/11 conspirators in federal courts will result in a plethora of legal and procedural problems that will severely limit or even jeopardize the successful prosecution of their cases.—

Attorney General Eric Holder and Defense Secretary Robert Gates strongly oppose the amendment, which they claim would “set a dangerous precedent.—

“We must be in a position to use every lawful instrument of national power, including both courts and military commissions, to ensure that terrorists are brought to justice,— the two administration officials wrote in a letter sent Friday to Majority Leader Harry Reid (D-Nev.) and Minority Leader Mitch McConnell (R-Ky.).

A handful of other GOP amendments have been offered to the spending measure, including one by Sens. Bob Bennett (Utah) and David Vitter (La.), which would require that the 2010 Census include a question on citizenship status. That amendment is not expected to be taken up with the bill.

Thursday’s procedural vote marks the second attempt by Reid to proceed to the C-J-S bill, which passed the House in June. The Senate’s 57-37 vote last month was just shy of reaching the 60-vote threshold to proceed to the bill.

Reid also announced Thursday the Senate will consider the nomination of Andre Davis, a judicial appointee nominated to the 4th Circuit. Davis was approved by the Judiciary Committee in June on a 16-3 vote.

Sen. Jim DeMint (R-S.C.) also has an amendment banning detainees held in Guantánamo Bay, Cuba, from being transferred to prisons in the United States. Like Graham’s amendment, DeMint’s amendment is opposed by the administration and poses a political risk for Democrats.