The National Rifle Association (NRA) announced on Monday that it would no longer use the law firm King & Spalding due to the firm's decision to withdraw from representing House Republicans in ongoing litigation challenging the constitutionality of the Defense of Marriage Act (DOMA), the 1996 law that bans federal agencies from recognizing the marriages of gay and lesbian couples, the Blog of Legal Times reported.

The Atlanta-based firm last week announced it would drop the case, prompting partner Paul Clement to jump ship to the Washington-based Bancroft PLLC, where he'll continue to work on the case. House leaders took on the task of defending the law after President Barack Obama announced he would no longer because he believes it to be unconstitutional.

In a letter to the law firm, NRA general counsel David Lehman criticized the firm's decision.

“We believe King & Spalding's decision is indefensible and raises serious concerns about its ability to be a reliable and effective advocate for any client facing potentially controversial litigation,” the letter said.

Conservatives have criticized the Human Rights Campaign (HRC) and other gay groups for pressuring King & Spalding to withdraw from the case.

The NRA is the second client to walk away from the prestigious law firm over its decision.

Last week, Virginia Attorney General Ken Cuccinelli said the firm would no longer be used by his office.