Chuck Hagel emerged as the top candidate for U.S. defense secretary Thursday, just as embattled U.N. Ambassador Susan Rice withdrew her name from consideration to succeed Hillary Rodham Clinton as secretary of state.

A Bloomberg News report identified Hagel, a Republican and former two-term U.S. senator from Nebraska, as the leading candidate for the defense job. A CNN source called Hagel the front-runner and another said his nomination was "almost a done deal."

Those reports came in the hours before Rice abruptly withdrew from consideration to be the next secretary of state. That followed an ugly standoff with Republican senators who declared they vigorously would oppose her nomination.

She had become the public face of the tangled administration description of what happened in Benghazi, Libya, on Sept. 11 of this year when four Americans, including the U.S. ambassador to Libya, were killed in what now is known to have been a terrorist attack.

Rice withdrew her name in a letter to President Barack Obama, saying she was convinced the confirmation process would be "lengthy, disruptive and costly -- to you and to our most pressing national and international priorities."

"That trade-off is simply not worth it to our country," Rice said.

Obama accepted her decision, with a shot at Republicans.

"While I deeply regret the unfair and misleading attacks on Susan Rice in recent weeks, her decision demonstrates the strength of her character," he said.

Rice's withdrawal elevates Massachusetts Sen. John Kerry as the likely choice to be the nation's next top diplomat when Clinton departs.

And it might have meaning for Hagel as well, since Kerry also has been named as a possibility for defense secretary.

An announcement on the defense job could come as soon as this month, Bloomberg News reported, but Obama hadn't made a final decision and the White House would not confirm the media speculation.

Other contenders for defense secretary include Michele Flournoy, former defense undersecretary for policy, and Ashton Carter, deputy defense secretary, Bloomberg reported, citing administration sources.

Several national media outlets have reported that Obama invited Hagel to the White House on Dec. 4 to discuss the position with him, and a Bloomberg source said Hagel told associates he is awaiting final word from the president.

Bloomberg's report also included a comment from former Nebraska U.S. Sen. Bob Kerrey, a Democrat whom Hagel supported in his unsuccessful bid to replace outgoing U.S. Sen. Ben Nelson. Hagel and Kerrey served together in the Senate and both are Vietnam War veterans.

“(Hagel) has the political skills to navigate some really treacherous waters,” Kerrey told Bloomberg. “He’ll enjoy wide respect in the military himself and, for a civilian leader, that’s important.

“He enjoys the confidence of the president and has a good relationship with the Senate,” he said. “He stayed very close to the current operational needs of the military.”