Attorney General Eric Holder on Thursday announced his resignation.

Holder, who assumed office on February 3, 2009, is the first black and fourth-longest-serving attorney general in US history.

President Barack Obama praised Holder, calling him “the people's lawyer,” during a press conference at the White House.

“Through it all, he's shown a deep and abiding fidelity to one of our most cherished ideals as a people, and that is equal justice under the law,” an emotional Obama said.

Holder has been an unequivocal ally to the LGBT community, refusing to defend the Defense of Marriage (DOMA) and extending legal benefits to gay couples.

Chad Griffin, president of the Human Rights Campaign (HRC), the nation's largest LGBT rights advocate, praised Holder as “our Robert F. Kennedy.”

“Some Attorneys General wait for history, others make history happen. Attorney General Holder made history for the LGBT community,” Griffin said. “He was our Robert F. Kennedy, lightening the burden of every American who faces legal discrimination and social oppression. We owe him a profound debt of gratitude for his legacy of advocacy and service.”

(Related: Eric Holder: State attorneys general “must be suspicious” of gay marriage bans.)