House Speaker John Boehner is looking for a new law firm to defend in court the Defense of Marriage Act (DOMA) after the Atlanta-based law firm King & Spalding on Monday announced it was withdrawing from the case.

Chairman Robert D. Hays, Jr. announced the reversal on Monday, POLITICO.com's Ben Smith reported.

“Today the firm filed a motion to withdraw from its engagement to represent the Bipartisan Legal Advisory Group of the House of Representatives on the constitutional issues regarding Section III of the 1996 Defense of Marriage Act,” Hayes said in a statement through a spokesman, Les Zuke. “Last week we worked diligently through the process required for withdrawal.”

“In reviewing this assignment further, I determined that the process used for vetting this engagement was inadequate. Ultimately I am responsible for any mistakes that occurred and apologize for the challenges this may have created.”

The announcement is a victory for gay rights groups which had criticized the firm for taking the case. The Human Rights Campaign (HRC) was expected to announce a campaign against King & Spalding's defense of the law that bans federal recognition of the marriages of gay and lesbian couples at a Tuesday press event in Atlanta.

Boehner appointed and led a committee that instructed House counsel to defend the law in court after the Obama administration announced it would no longer do so. The president has said he believes parts of the law are unconstitutional.

Opponents of gay marriage had cheered the news that Paul Clement, a partner in the Washington, D.C. office of the firm, would lead the case.

“At last we have a legal eagle on this case who actually wants to win in court!” Brian Brown, president of the National Organization for Marriage (NOM), said in a statement. “Paul Clement is a genuinely distinguished lawyer, a former solicitor general of the United States, who we are confident will win this case. Thanks to Speaker Boehner's actions, President Obama's attempt to sabotage the legal defense of DOMA is not going to work.”