Attorney General Eric Holder reiterated Friday that the Justice Department will file a brief in support of same-sex couples’ right to marry should the U.S. Supreme Court again consider the issue.

In an interview with NBC News one day after Holder announced he would step down, the nation’s first African-American attorney general said a brief filed by the Justice Department would be consistent with positions they have taken in the past on same-sex marriage.

“I expect that the Justice Department will file a brief and the brief will be consistent with the positions that we have taken in the past in support of same-sex marriage,” Holder told Pete Williams of NBC News. “I can’t imagine that we would take any other position while this president is in office and certainly as long as I am attorney general or anybody who is my successor.”

According to the nation’s top lawyer, who will stay on until President Barack Obama names his successor, the country is ready for such a move.

“I think al the polls certainly show that, the reactions to the continuing number of court cases that have found same-sex marriage to be constitutionality mandated. The polls have shown that the American people are prepared to accept that,” Holder said. “Now this has been a sea change. This is something that has happened relatively quickly, part of it is generational. I talk to my kids who see no problems with this, no issues with this at all. But I think it is more than a generational change. I think that people who know folks who are gay, who are lesbian and who are their friends, their coworkers — they see the moral side to this. It’s a civil rights issue. From my perspective it is the civil rights issue of our day, gay and lesbian equality.”

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Holder has been a champion of LGBT-rights during his nearly six year as attorney general. In February 2011, Holder announced the Obama administration and the Justice Department would no longer defend the constitutionality of Section 3 of the Defense of Marriage Act (DOMA), which defined marriage as between a man and a woman for federal purposes. In June 2013, the U.S. Supreme Court struck down Section 3 of DOMA in a sweeping decision that has led federal and state courts to overturn state bans on same-sex marriage across the country. Holder himself has given state attorneys general the green light to stop defending bans on same-sex marriage.

When the Supreme Court did throw out the federal government’s definition of marriage as between a man and a woman, Obama was quick to act. On June 26, 2013, the same day the Windsor decision was issued, Obama instructed the Justice Department to work with members of his cabinet to ensure the decision was implemented swiftly and broadly across the federal government. Nearly one year later, Holder announced the decision had been implemented across the federal government “to the greatest extent possible under the law” in a memo to Obama.

During an interview with ABC News in July, Holder first indicated that when the issue of marriage equality once again comes before the nation’s highest court, the Obama administration will file a brief advocating for same-sex couples’ right to marry.

On Monday, Sept. 29, the Supreme Court justices will meet behind closed doors to consider seven petitions asking the high court to hear cases challenging same-sex marriage bans in five states: Utah, Oklahoma, Virginia, Indiana and Wisconsin. The Supreme Court has no obligation to take any of the cases, nor are they restricted to a specific timeframe for announcing their decisions, but the speed at which the issue has returned back to the nation’s highest court is noteworthy.

“Once again, Attorney General Eric Holder and the Obama Administration have stood up for marriage equality at a critical moment,” said Chad Griffin, president of the Human Rights Campaign, in a statement. “As the nine justices of the U.S. Supreme Court gather on Monday to evaluate several marriage equality cases for full hearing, I hope they consider two facts—that the nation is ready for marriage equality, and that there are painful consequences to inaction. Committed and loving gay and lesbian couples can’t afford to wait any longer. It’s time to settle this constitutional question, once and for all.”

Asked to name his proudest accomplishments as attorney general, Holder noted civil rights, efforts by the Justice Department to ensure the “most fundamental of rights,” the right to vote, and criminal justice reform. Moreover, he added, “What we’ve done for LGBT equality, same-sex marriage — I’m very proud of that.”

Watch the full interview: