UN ambassador Susan Rice on Friday defended her record and lamented the partisan politics that she said had forced her to withdraw from consideration for the post of US secretary of state.

UN ambassador Susan Rice, pictured on November 29, 2012, has defended her record and lamented the partisan politics that she said had forced her to withdraw from consideration for the post of US secretary of state.

In a Washington Post op-ed Rice defended her controversial statements about the deadly September 11 attack on a US mission in Libya and struck back at Republican lawmakers who had vowed to block her path to becoming top diplomat.

"As it became clear that my potential nomination would spark an enduring partisan battle, I concluded that it would be wrong to allow this debate to continue distracting from urgent national priorities," Rice wrote.

The longtime member of President Barack Obama's inner circle and favorite to succeed Hillary Clinton had announced Thursday that she was removing herself from consideration for the post, despite never being formally nominated.

Her role as a top administration defender over the attack which killed the US ambassador to Libya and three other Americans drew her into a furious row with Republicans keen to dent Obama after his re-election victory.

Rice defended her appearance on Sunday talk shows five days after the attack, when she characterized the assault as a "spontaneous" response to an offensive anti-Islam video and not a pre-planned act of terrorism.

"I relied on fully cleared, unclassified points provided by the intelligence community, which encapsulated their best current assessment," she wrote.

"The intelligence community did its job in good faith. And so did I. I have never sought in any way, shape or form to mislead the American people."

She said her decision to bow out was motivated by a desire to defuse the partisan bickering that threatened to undermine Obama's second-term agenda of striking a far-reaching budget deal and reforming immigration.

"A national security appointment, much less a potential one, should never be turned into a political football. There are far bigger issues at stake. So I concluded this distraction has to stop," she wrote.

The president and his UN envoy will meet Friday at the White House.

Rice's move came as Obama appeared to be making progress in naming his new national security team. Sources said Republican former senator Chuck Hagel could become secretary of defense.

The White House, haggling with Republicans over taxes and spending, had pragmatically concluded the political capital needed to confirm Rice in the Senate could be better spent elsewhere.

But some observers may sense weakness in Obama's decision not to fight for Rice against opposition from Republicans -- including the man he defeated for the White House in 2008, Senator John McCain.

Obama, who aides say is philosophically and personally close to Rice, issued a statement Thursday condemning the "unfair and misleading attacks" on her and said she would stay on as UN ambassador with a spot on his cabinet.

Republicans pounced on Rice after she said on September 16 that the Benghazi attack was a "spontaneous" reaction to the anti-Muslim video, using CIA talking points she now admits were wrong.

Extremists linked to Al-Qaeda are now blamed for the attack, and Republicans charge the White House did not want to own up to a terror attack weeks before the presidential election.

Rice faced other potential obstacles: there were whispers over her apparently acerbic character, and criticism over her role in US diplomacy to Africa when she served in Bill Clinton's administration.

McCain, who was one of Rice's fiercest critics, issued a statement from his office in which he thanked Rice for her public service and wished her well but vowed to continue to investigate the Benghazi attack.

Clinton, who has said she will not serve in Obama's second term, praised Rice as "an indispensable partner over the past four years."

And Rice told her followers on Twitter that she was a "fighter" who still had work to do for the American people, amid speculation that she could eventually be named as Obama's national security advisor.

Obama is meanwhile considering Hagel for defense secretary to succeed Leon Panetta, sources said.

A decision by Obama to pick a Republican to lead the Pentagon would be seen as an attempt to show bipartisanship, although Hagel is seen as a centrist on foreign policy who has broken with his party on several key issues.

The president must also find a new head for the CIA.