WASHINGTON (AFP) - President Barack Obama on Saturday praised his pick for the next attorney-general who, if confirmed, will become the first black woman to hold the post.
Loretta Lynch, 55, is a dogged prosecutor with years of front-line experience that would make her an ideal fit to become America's top law enforcement official, the President said.
"It's pretty hard to be more qualified for this job than Loretta," Obama said at the White House as he officially announced Lynch's nomination.
"She has spent years in the trenches as a prosecutor, aggressively fighting terrorism, financial fraud, cybercrime, all while vigorously defending civil rights."
Her confirmation is still subject to Senate approval by the Republicans, who now control both houses in the Congress after this week's election rout of the Democrats.
They want to wait until newly elected lawmakers assume their positions in the New Year before voting on Lynch's confirmation.
However, she is not seen as a member of Obama's inner circle - which may make her seem less polarising and help her in process.
Holder - who agreed to stay on until his successor is confirmed - is seen as a champion of civil rights by supporters but reviled as an ideologue by Republicans.
Chuck Grassley, the top Republican on the Senate Judiciary Committee said Friday that he hoped Lynch's tenure, if confirmed, would "restore confidence in the attorney-general as a politically independent voice for the American people."
Obama praised Lynch's experience prosecuting the cases of plots to bomb the Federal Reserve and the New York subway system.
"Loretta might be the only lawyer in America who battles mobsters and drug lords and terrorists, and still has the reputation for being a charming 'people person,'" Obama said.
"Loretta doesn't look to make headlines, she looks to make a difference. She's not about splash, she is about substance," the President added.
Obama also praised his friend Holder, saying America was "safer and freer" because of his work.
Lynch, 55, would be the second African-American attorney-general, after Holder.
"No one gets to this place, this room, this podium, this moment by themselves," she said during brief comments in which she thanked Obama, Holder, colleagues and others.
"If I have the honour of being confirmed by the Senate, I will wake up every morning with the protection of the American people my first thought," she said.
Lynch is in her second stint as the top federal prosecutor for the Eastern District of New York. She earned Senate confirmation under president Bill Clinton and again in 2010 under Obama.
Lynch first came to prominence as a member of the legal team that prosecuted and won convictions in a high-profile case against uniformed New York City police officers who beat and sexually assaulted Haitian immigrant Abner Louima after arresting him.
A North Carolina native, Lynch has both undergraduate and law degrees from Harvard University.
As for Holder, Obama has called his departure "bittersweet," but said he empathised with the sacrifices he and his family had made as he served in one of the toughest jobs in government.
He is one of just three original Cabinet members still serving in the job they took when Obama assumed power in 2009, alongside Education Secretary Arne Duncan and Agriculture Secretary Tom Vilsack.
Only three other US attorneys-general have served longer than Holder, whose tenure was notable for significant inroads made in the civil rights arena, including gains in rights and benefits for same-sex couples and reductions in prison sentences for certain drug offences.