As news comes that two prominent lawyers have challenged Proposition 8, pro-family supporters say they will “vigorously oppose” any further efforts in state and federal courts to invalidate or weaken the successful 2008 California ballot measure which restored the definition of marriage to being between a man and a woman.

On Tuesday the California Supreme Court upheld the constitutionality of Prop. 8 by a 6-1 vote.

ProtectMarriage.com, the group representing supporters of Proposition 8, said in a statement that it would “vigorously oppose” any further state and federal court efforts to invalidate the law.

Former U.S. Solicitor General Ted Olson, who served in the George W. Bush administration, and David Boies, a prominent lawyer who represented Al Gore in the legal fight following the 2000 presidential election, have filed a preliminary injunction in federal court calling for an injunction on the California Supreme Court decision.

According to the Los Angeles Times, the two filed suit on Friday in U.S. District Court for the Northern District of California arguing that Prop. 8 makes homosexuals “second-class citizens” and violates the U.S. Constitution’s equal protection guarantees.

Olsen and Boies are co-counsels for the lawsuit, which is the first project of a new organization called American Foundation for Equal Rights.

ProtectMarriage.com said that efforts to legalize same-sex “marriage” must now “go to the people and seek their permission—something they have never done.”

Andrew Pugno, chief counsel for the group, reacted to news of the lawsuit by saying, "Just one day after the California Supreme Court upheld Prop 8, the will of the voters is under attack once again.  This new federal lawsuit, brought by a pair of prominent but socially liberal lawyers, has very little chance of succeeding.  But we will take it seriously and take action to provide a vigorous defense of Prop 8, just as we did in the California courts.”

Ron Prentice, Chairman of the ProtectMarriage.com Executive Committee said the group will change focus to the long-term goal of protecting marriage and strengthening family values.

“We will now turn our attention to public education and outreach so that citizens come to better understand and appreciate the many benefits that traditional marriage provides for society and our families,” Prentice said.

“The institution of marriage as we have always understood it has served California and our broader society since the nation was founded. We look forward to working with young people, churches, ethnic communities and all of California with an ongoing discussion about the benefits of traditional marriage.”