The self-proclaimed mastermind of the Sept. 11 attacks and four other alleged terrorists will be tried in a federal court in New York, not before a military tribunal, according to unnamed sources cited by The Associated Press.

Attorney General Eric Holder will reportedly announce at a press conference scheduled for later Friday morning his decision to use civilian proceedings to prosecute suspect Khalid Sheikh Mohammed and those who worked with him.

Holder is also expected to announce that the leading suspect in the 2000 bombing of the USS Cole, Abd al-Rahim al-Nashiri, will face justice before a military commission, along with several other Guantánamo Bay detainees.

Ultimately, Friday's string of announcements fulfills the White House's promise to inform a Guantánamo Bay military judge by Monday where it wanted to try many of the base's prisoners, a decision central to Obama's pledge to close the facility by January.

However, the White House is sure to face serious political opposition for Friday's move, especially its decision to try Sept. 11 suspects domestically in civilian court.

While the president has long maintained that different courts are better suited to handle different cases, some conservatives have regarded even the thought of affording Sept. 11 suspects the right of a federal trial as utter anathema.

A smattering of Republican lawmakers and a coalition of victims' families even tried to pre-empt Friday's announcement last week, hoping to encourage the Obama administration to try at least the alleged Sept. 11 terrorists before military tribunals.

"We believe that military commissions, which have had a long and honorable history in this country dating back to the Revolutionary War, are the appropriate legal forum for the individuals who declared war on America," 143 family members of Sept. 11 victims wrote last week in an open letter to Senate lawmakers, who were considering Sen. Lindsey Graham's (R-S.C.) proposed amendment to bar Sept. 11 suspects from federal courts.

"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," they added.

However, Graham's effort was ultimately shelved last Thursday on a close, 54-45 vote.

“If this amendment passes, it will say that the only people in the world who cannot be tried in the courts of America for crimes of terrorism are those who are accused of terrorism on 9/11,” said Senate Majority Whip Dick Durbin (D-Ill.) before the floor vote.