"While Americans want Washington to focus on creating jobs and cutting spending, the president will have to explain why he thinks now is the appropriate time to stir up a controversial issue that sharply divides the nation," said Brendan Buck, a spokesman for House Speaker John Boehner.
"It is a transparent attempt to shirk the [Justice] Department's duty to defend the laws passed by Congress," said Republican Rep. Lamar Smith of Texas, who chairs the House Judiciary Committee, in a statement. "This is the real politicization of the Justice Department-- when the personal views of the President override the government's duty to defend the law of the land."
DOMA was passed by a Republican House and Senate and signed into law by Democratic President Bill Clinton in 1996. The law means same-sex couples are not afforded the same rights as straight couples when it comes to Social Security benefits, hospital visitation and other rights.
White House spokesman Jay Carney said that while the administration would not defend DOMA it would remain a party in the legal cases so that they can proceed to a judgment and allow other interested parties the opportunity to step in and defend the law if they wish.
"The administration will do everything it can to assist the Congress if it so wishes to do that," Carney said. "We recognize and respect that there are other points of view and other opinions about this."
In California, where neither Gov. Arnold Schwartzenegger nor Gov. Jerry Brown, nor their attorneys general, chose to defend the state's ban on same-sex marriage, they remained parties in the case, allowing outside groups to provide legal counsel to defend the law.
In June 2009, for example, Obama's Justice Department invoked incest and adults marrying children as reasons to uphold DOMA.
Last month, then-White House press secretary Robert Gibbs said that "we can't declare the law unconstitutional…The president believes, as you said, that this is a law that should not exist and should be repealed. But we, at the same time, have to represent the viewpoint of the defendant."
Gibbs said that "given the current makeup of the Congress," having DOMA repealed would be "inordinately challenging."
The administration may now be hoping that a federal court will strike down the law nationwide, officially rendering it null.
In July 2010, a federal district court judge ruled DOMA unconstitutional. But the case remains on appeal.
Personally, the president does not support gay marriage, saying instead that he supports strong civil unions for gay and lesbian couples. But his opinion may be changing.
"He's grappling with the issue," Carney said today. "But he -- again, I want to make the distinction between his personal views, which he has discussed, and the legal issue, the legal decision that was made today. "
At a news conference in December of 2010, shortly after signing into law a repeal of the military's "don't ask don't tell' policy toward gay service members, Obama said of gay marriage, "My feelings about this are constantly evolving."