By PETER NICHOLAS and JULIAN E. BARNES

U.N. Ambassador Susan E. Rice withdrew from consideration to be secretary of state on Thursday in anticipation of a fierce confirmation battle with Republican opponents, marking the first political defeat for President Barack Obama in preparing for his second term.

U.N. Ambassador Susan Rice removed her name from consideration for the secretary of state job. In a letter to the president, she said the confirmation process would be “disruptive.” Jerry Seib has details on The News Hub.

Ms. Rice’s announcement that she was ending her bid for the post could reverberate across two branches of government, reshaping Mr. Obama’s cabinet selections and possibly changing the makeup of the U.S. Senate.

Mr. Obama has yet to nominate anyone to succeed Hillary Clinton, who has said she doesn’t want to stay on as the nation’s top diplomat in a second term. But officials had said Ms. Rice was the leading candidate, and Mr. Obama had defended her from detractors.

“While I deeply regret the unfair and misleading attacks on Susan Rice in recent weeks, her decision demonstrates the strength of her character, and an admirable commitment to rise above the politics of the moment to put our national interests first,” Mr. Obama said in a statement released by the White House.

In a letter to the president, Ms. Rice wrote she had been honored to be considered. “However,” she added, “if nominated, I am now convinced that the confirmation process would be lengthy, disruptive and costly—to you and to our most pressing national and international priorities.”

The leading candidate to helm the State Department now becomes Sen. John Kerry (D., Mass.), chairman of the Senate Foreign Relations Committee. Mr. Kerry has played a central role in many of Mr. Obama’s most important foreign policy initiatives in recent years. Unlike Ms. Rice, the former Democratic presidential nominee is viewed by his Senate colleagues as having the international stature to step into one of the most prestigious cabinet posts.

“As someone who has weathered my share of political attacks and understands on a personal level just how difficult politics can be, I’ve felt for her throughout these last difficult weeks,” Mr. Kerry said in a statement. He didn’t comment on his possible nomination to the Secretary of State post.

Ms. Rice’s confirmation was jeopardized by her role in explaining the Sept. 11 attack this year on a U.S. consulate in Libya that killed four Americans, including U.S. Ambassador Christopher Stevens. Republicans scorned her for saying on TV talk shows days after the attack that protests over an anti-Islamic video had sparked the violence, rather than calling the incident a deliberate act of terrorism. Ms. Rice later said she relied on information furnished by intelligence officials.

Pursuing the nomination in the face of Republican opposition, led by GOP Sens. John McCain of Arizona and Kelly Ayotte of New Hampshire, among others, would have put Mr. Obama on track for a protracted battle at the same time he is in tense negotiations over a deficit-cutting deal to avoid year-end tax increases and spending cuts known as the fiscal cliff.

An additional fight over a Rice nomination wouldn’t have been helpful, said Sen. Bob Corker (R., Tenn.). “To add this to the equation probably would have been more than any of us could bear,” he said.

Mr. Corker, who’s set to become the top Republican on the Senate Foreign Relations Committee, said he doubted that Ms. Rice could have been confirmed. Republican senators “felt she was more of a political operative than a principal,” Mr. Corker said of Ms. Rice.

The White House declined to comment on future appointments. Personnel announcements won’t be made this week and might not happen before Christmas, one Obama administration official said.

Mr. Kerry also has been in the running for Defense secretary. Should he be tapped for the State Department, that might clear the way for the president to appoint former Nebraska senator Chuck Hagel, a moderate Republican, to replace Leon Panetta as secretary of defense. Mr. Panetta hasn’t said when he will step down but has indicated he wants to return to private life next year, resuming work at his family foundation and his walnut farm in California.

Mr. Hagel has met privately with the president to discuss the Defense Department post and has emerged as a top contender, according to current and former administration officials. Installing Mr. Hagel as Pentagon chief would give the cabinet more of a bipartisan cast, something Mr. Obama has made clear he wants. A spokesman for Mr. Hagel declined to comment.

Should Mr. Kerry become secretary of State, his open Senate seat would be a tempting target for Republican Sen. Scott Brown of Massachusetts, who lost a bid for re-election last month to Democrat Elizabeth Warren. Having spent tens of millions of dollars in the recent contest, Mr. Brown has the broad name recognition in his home state that would be needed to win a special election for Mr. Kerry’s seat. Mr. Brown’s spokesman didn’t respond to a request for comment.

Current and former officials expect the White House to announce at the same time the nominees for State, Defense and director of Central Intelligence. The two leading candidates for CIA director to replace David Petraeus, who resigned last month, are John Brennan, the White House counter terrorism coordinator, and the acting director, Michael Morell. Mr. Brennan emerged during the first term as one of Mr. Obama’s most trusted advisers. Officials have said that Mr. Brennan, a former CIA official, would like to leave the White House and would like the top post at CIA.

Several senators, including Ms. Ayotte, have said the next nominee to lead the agency would face questions on the agency’s handling of the Benghazi attacks, particularly if it is someone who has been at the CIA. Several Republican senators have raised questions about whether the intelligence that CIA officials gave to the administration about the Benghazi attacks was faulty.

Raised in the District of Columbia, Ms. Rice, 48, attended Stanford University and was selected as a Rhodes scholar. During the Clinton administration, she worked on African affairs in the White House National Security Council, then as assistant secretary of state for African affairs.

As recently as last month, the president seemed determined to fight for Ms. Rice’s promotion. He was coming off a decisive re-election victory and defended her in terms that suggested he would not shun a fight with Republicans over her elevation.

Mr. Obama said at a White House news conference that Ms. Rice had been unfairly criticized for the interviews about the Libya attacks, which she had given at the request of the White House.

“If Sen. McCain and Sen. Graham and others want to go after somebody, they should go after me,” Mr. Obama said, referring Ms. Rice’s detractors, who included Sen. Lindsey Graham of South Carolina. “But for them to go after the U.N. ambassador, who had nothing to do with Benghazi, and was simply making a presentation based on intelligence that she had received, and to besmirch her reputation is outrageous.”

If appointed, Mr. Hagel would follow in the footsteps of Robert Gates and Sen. Bill Cohen of Maine as centrist Republicans who have served as secretary of defense under Democratic presidents. Mr. Hagel is known for crossing party lines. Although he supported the initial invasion of Iraq in 2003, he soured on the war and in March, 2007, backed a Democratic bill that called for then-President George W. Bush to begin withdrawing forces from Iraq. He also supported Mr. Obama’s 2008 run for the White House over that of Mr. McCain, who was Mr. Hagel’s Senate colleague.

In interviews, Mr. Hagel has called the Pentagon budget bloated and said that it can be trimmed, a position that squares with that of the Obama White House.

—Carol E. Lee, Naftali Bendavid and Jay Solomon contributed to this article.Write to Peter Nicholas at [email protected] and Julian E. Barnes at[email protected]