Washington (AFP) - The US Senate confirmed Loretta Lynch as the nation's first black female attorney general Thursday, installing an aggressive counter-terrorism prosecutor as the top law enforcement official for President Barack Obama's final 21 months in office.

Lynch was confirmed in a 56-43 vote -- with 10 Republicans crossing the political aisle to lend their support -- following weeks of gridlock after her confirmation process was dragged into a bitter partisan battle over abortion.

She takes over from outgoing Attorney General Eric Holder, whom Republicans had criticized as being a rubber stamp for Obama's policies.

Lynch's confirmation brought to an end a months-long process that Democrats noted took longer than the confirmation of the seven previous attorneys general combined.

"Today, the Senate finally confirmed Loretta Lynch to be America's next attorney general -– and America will be better off for it," Obama said in a statement.

"Loretta has spent her life fighting for the fair and equal justice that is the foundation of our democracy."

Lynch, 55, has served twice as US Attorney for the Eastern District of New York, where she thrived as a relentless federal prosecutor putting mobsters and terror suspects behind bars.

Her office has prosecuted more terrorism cases since the 9/11 attacks of 2001 than any other office, noted Democratic Senator Amy Klobuchar, who described Lynch as "exactly the type of tough and tested leader" Americans need in the job.

With her confirmation dragging on, Lynch dived into her work as US attorney. Just this Monday, she announced a 25-year prison sentence for an American from New York who admitted he tried to join an Al-Qaeda group.

In previous years, she successfully prosecuted the terrorists who plotted to bomb the Federal Reserve Bank and the New York subway.

She also went after corrupt public servants and politicians in both parties, and won billions of dollars in settlements in fraud cases involving major banks.

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And she oversaw the civil rights prosecution of several New York Police Department officers involved in the brutal 1997 assault of Haitian immigrant Abner Louima, which could provide key perspective as she investigates a series of recent cases involving the use of deadly police force against Americans.

With Republicans seething over what they argue is White House overreach, many expressed hope that Lynch, who would be only the second woman to hold the post after Janet Reno (1993-2001), would strike a less overtly political and combative tone than Holder.

- 'Embodiment of American Dream' -

At her confirmation hearing in January, Lynch said she would act independently and aimed to build a "new and improved relationship" with Congress, where Republicans who control both chambers are incensed with Obama's unilateral actions last year on immigration.

Hours before the vote, Senator Ted Cruz attacked Lynch as unfit for the position and "unwilling to impose any limits whatsoever on the authority of the president of the United States."

Despite urging colleagues to stop Lynch, Cruz, a candidate for president in 2016, was the lone senator not to vote on Lynch's confirmation.

Lynch is the daughter of a North Carolina Baptist minister father and a librarian mother. Fascinated with the legal system since she was a child, Lynch attended Harvard College and then Harvard Law School.

"This woman is the embodiment of the American Dream in action," Senator Claire McCaskill said.

Lynch's father was seen in the Senate gallery and several House members in the Congressional Black Caucus were invited to the Senate floor for the historic vote.