A federal judge ruled Wednesday that a group of legal organizations will not be allowed to join a high-profile lawsuit challenging California’s Proposition 8, now set for a January trial date.

Judge Vaughn R. Walker of the U.S. district court for Northern California denied a motion to intervene by the National Center for Lesbian Rights, Lambda Legal, and the American Civil Liberties Union. The three legal groups had sought to represent several California LGBT community groups in the case, a move strongly opposed by Ted Olson and David Boies, the attorneys who filed the suit in May.

The two attorneys have argued that adding more parties to the legal battle would delay a swift resolution of the case.

The Alliance Defense Fund, a right-wing legal organization, already has been allowed to intervene to defend Prop. 8 in federal court.

Lambda, the NCLR, and the ACLU expressed immediate dismay at the ruling on Wednesday.

“On behalf of our clients, we are disappointed that the court did not permit organizations that represent California’s diverse lesbian, gay, bisexual, and transgender (LGBT) community to participate in the case as the Court weighs the harms inflicted by Proposition 8,” the coalition said in a joint statement. “The significance of this case for our entire community is enormous. To exclude the people whose very freedom is at stake is troubling.”

Judge Walker has allowed intervention by the City of San Francisco, which also filed a motion to join the case, but only to examine Prop. 8’s impact on local government, according to the Associated Press.

The judge has set a court hearing for January 11, 2010.