Gay rights groups have altered course and joined a federal gay marriage lawsuit likely headed to the Supreme Court, the AP reported.

In legal briefs filed Thursday, the National Center for Lesbian Right, Lambda Legal and the American Civil Liberties Union (ACLU) backed a federal lawsuit spearheaded by former U.S. Solicitor General Theodore Olson and David Boies.

The two legal titans are representing a gay couple and a lesbian couple who would like to marry in California but cannot because of Proposition 8, the state's voter-approved gay marriage ban upheld as constitutional by the state Supreme Court in May. The lawsuit argues that Proposition 8 violates the U.S. Constitution.

Previously the ACLU had called fighting the gay marriage ban in federal court a “very high risk proposition.”

“Successful change involves building blocks,” Matt Coles, director of ACLU's LGBT project, told the Wall Street Journal's law blog. “You build constitutional principles alongside efforts at the societal and legislative levels. They're jumping over the process and going straight to the end. From where we sit, this is a very high-risk proposition.”

“In our view, the best way to win marriage equality nationally is to continue working state by state, not to bring premature federal challenges that pose a very high risk of setting a negative U.S. Supreme Court precedent,” Shannon Minter, legal director of National Center for Lesbian Rights, told the AP.

While a win in the Supreme Court would open gay marriage nationwide, a loss would likely set the movement back possibly decades; leaving gay activists to call the move “premature.”

Early on, gay rights groups and activists questioned the motivations behind the lawsuit. Olson in particular was singled out for his long record of counseling conservative, often anti-gay, leaders, former President Bush included. The three groups now say they support the federal lawsuit and the arguments of Olson and Boies.