In a move that could give gay marriage its first foothold in the South, Virginia's attorney general said Thursday he concluded the state's ban on same-sex unions is unconstitutional and he will join the fight against it.

Newly-elected Democratic Attorney General Mark R. Herring said he would support gay couples who have filed lawsuits challenging the state's ban.

"After thorough legal review, I have now concluded that Virginia's ban on marriage between same sex couples violates the Fourteenth Amendment of the U.S. Constitution on two grounds: Marriage is a fundamental right being denied to some Virginians, and the ban unlawfully discriminates on the basis of both sexual orientation and gender," Herring said.

As a state Senator in 2006, Herring voted against permitting same-sex couples to marry, but he sys his personal views have changed.

"I have just come to the conclusion I would not want the state telling my son or daughter who they can and cannot marry," he said.

His decision does not change the law. The ban will continue to be enforeced in county clerks' offices.

Herring's announcement comes on the heels of court rulings in which federal judges struck down gay marriage bans in Utah and Oklahoma.

Currently the District of Columbia and 17 states allow gay marriage, most of them clustered in the Northeast. None of them is in the old Confederacy. Virginia is widely considered a battleground state in the same-sex marriage debate.

Herring's decision drew divided responses.

Tom Shuttleworth, representing the couples challenging the state ban, praised Herring's position "on the basic human right of being able to marry the person of your choice."

"It's a nice day to be an American from Virginia," he wrote in an email.

But the conservative Family Foundation of Virginia called the development "disappointing and frightening."

The Republican speaker of the Virginia House of Delegates said Herring was setting a "dangerous precedent."

"The attorney general has a constitutional and statutory obligation to enforce and defend the duly adopted laws and Constitution of Virginia," William J. Howell said in a statement. "This is not an obligation that can be taken lightly."

Del. Bob Marshall (R-Prince William County), who was one of the authors of the law, said that if the attorney general will not defend the law, he's required to appoint someone who will.

Herring's announcement comes weeks after Democrats swept the top of the November ballot and took office, changing the state's political landscape.

With the election of Democrats Terry McAuliffe as governor and Herring as attorney general, Virginia made a hairpin turn away from the socially conservative officeholders they succeeded, particularly Republican Attorney General Ken Cuccinelli, an activist on social issues such as abortion and gay marriage.

McAuliffe issued an executive order on inauguration day prohibiting discrimination against state employees who are gay.

Virginia voters approved the same-sex marriage ban 57 percent to 43 percent in 2006. But a Quinnipiac University poll in July found that 50 percent of registered Virginia voters support same-sex marriage, while 43 percent oppose it. The survey's margin of error was plus or minus 3.1 percentage points.

It is not the first time an attorney general has decided to stop defending their state's gay marriage ban. In Pennsylvania, Attorney General Kathleen Kane said last year that she would stop defending that state's gay marriage ban, also calling it unconstitutional. An outside law firm was hired to represent the state in a lawsuit over the ban.

Proponents of striking down the state's ban say the issue resonates in Virginia in particular because of a landmark 1967 U.S. Supreme Court decision involving a Virginia couple and interracial marriage.

Mildred and Richard Loving were married in Washington, D.C., and were living in Virginia when police raided their home in 1958 and charged them with violating the state's Racial Integrity law. They were convicted but prevailed before the Supreme Court.

"Virginia has argued on the wrong side of some of our nation's landmark cases," Herring said. "It's time for the Commonwealth to be on the right side of history and the right side of the law."

The fight in Virginia is being partially paid for by the American Foundation for Equal Rights, which was behind the effort to overturn California's gay marriage ban.

David Boies and Theodore B. Olson, the high-profile legal tandem that brought down California's prohibition on same-sex marriage, lead the legal team in that challenge. Both cited Virginia's history when they announced their challenge.

"This case is about state laws that violate personal freedoms, are unnecessary government intrusions, and cause serious harm to loving gay and lesbian couples," Olson had said.

The Norfolk lawsuit's plaintiffs are two couples: Timothy Bostic and Tony London, and Carol Schall and Mary Townley.

Bostic and London applied for a marriage license with the Norfolk Circuit Court Clerk's office in July 2013, but their application was denied.

Schall and Townley were legally married in California in 2008. They have a daughter, whom Townley gave birth to in 1998, but Schall can't adopt her because Virginia law doesn't allow same-sex couples to adopt children, according to the lawsuit.

The lawsuit argues that Virginia law stigmatizes gay men and lesbians, along with their children and families, because it denies them the same definition of marriage afforded to opposite-sex couples.

In that state General Assembly, Democratic legislators are still widely outnumbered in the House of Delegates, but they have been emboldened by the shift away from a reliably conservative state. They took immediate aim at the state's ban on gay marriage, but proposed constitutional amendments face a long road. The earliest voters could see a proposed amendment is in 2016.