WASHINGTON (AP) — A moderate Republican senator, vital to any White House hopes of getting U.N. Ambassador Susan Rice confirmed as secretary of state, said Wednesday she couldn’t back any nomination until more questions are answered about the deadly Sept. 11 attack in Libya and Rice’s State Department role during the 1998 U.S. Embassy bombing in Kenya.

In a fresh suggestion of eroding GOP support for Rice, Sen. Susan Collins of Maine emerged from a 90-minute, closed-door meeting with the ambassador voicing new criticism of her initial account about Libya. Collins also questioned what Rice, the assistant secretary of state for African Affairs in the Clinton administration, knew about requests for enhanced embassy security before the Nairobi truck bombing.

Pressed on how she would vote if President Barack Obama names Rice to succeed Secretary of State Hillary Rodham Clinton, Collins said, “I would need to have additional information before I could support her nomination.”

President Barack Obama came to Rice’s defense during a Cabinet meeting, calling her “extraordinary” and saying he couldn’t be prouder of the job she has done as U.N. ambassador. Cabinet members joined Obama in applauding Rice, who attended the meeting. Obama has not named a replacement for Clinton, who has said she intends to step down soon.

At the State Department, Clinton was asked about her possible replacement.

“Susan Rice has done a great job as our ambassador to the United Nations,” Clinton said. “Of course, this decision about my successor is up to the president, but I am very happy he has the opportunity with a second term to make a decision.”

The misgivings from Collins, the top Republican on the Homeland Security Committee, came one day after three other GOP senators said they would try to block Rice’s nomination. Sens. John McCain of Arizona, Lindsey Graham of South Carolina and Kelly Ayotte of New Hampshire said they were more troubled than ever by Rice’s answers on Libya even though the ambassador conceded that her much-maligned first explanation was wrong.

In an unusual move, Rice and acting CIA Director Michael Morell have held two days of private meetings with Republican senators in hopes of assuaging their concerns. Privately, Senate Republicans said they had hoped the conversations would quiet the criticism as they want to avoid the spectacle of a postelection challenge to a female African-American nominee.

Instead, the sessions have cast further doubt on her chances for the top State Department job and increased the likelihood of a protracted fight if Obama does choose her. Although Democrats will have 55 votes in the next Congress, the president would need the support of five Republicans to avoid a filibuster of the nomination. Collins would be a prime candidate to help avoid a filibuster of the nomination.

Collins said she was troubled by Rice’s “political role” in downplaying the Libya attack as a spontaneous demonstration over an anti-Muslim video rather than a terrorist attack by al-Qaida affiliates in a series of Sunday talk show appearances on Sept. 16 — five days after the attack and weeks before the election.

U.S. Ambassador Chris Stevens and three other Americans were killed in the raid on the U.S. diplomatic mission.

Rice has said she was relying on talking points provided by U.S. intelligence.

Introducing another issue certain to be fodder for any confirmation battle, Collins said she pressed Rice about security at the U.S. Embassy in Nairobi in 1998 when a truck bomb was set off outside the facility, killing more than 200 Kenyans and 12 Americans.

“What troubles me so much is the Benghazi attack in many ways echoes the attacks on those embassies in 1998 when Susan Rice was head of the African region for our State Department,” Collins told reporters after the meeting. “In both cases, the ambassador begged for additional security.”

Collins said Rice told her she was not involved directly in turning down the request for improved security. The Maine senator said that in light of Rice’s position, she had to be aware of the general threats and U.S. Ambassador Prudence Bushnell’s requests for security upgrades in Kenya.

Review boards headed by former Joint Chiefs of Staff chairman Adm. William J. Crowe after the Aug. 7, 1998, bombings of the U.S. embassies in Kenya and Tanzania did not find reasonable cause that any U.S. employee breached his duty in connecting with the bombings. Rice was not blamed.

However, Crowe said the boards believed there was a “collective failure” by several administrations and Congress over a decade to invest adequately to shore up vulnerable U.S. diplomatic missions around the world.

Rice has emerged as the front-runner for the top job at State, though Senate Foreign Relations Committee Chairman John Kerry, D-Mass., passed over for the job in 2008, is considered a strong alternative.

In a clear message to the White House, Collins said Kerry would have no problem winning Senate confirmation.

“I think John Kerry be an excellent appointment and would be easily confirmed by his colleagues,” Collins said.

Sen. Bob Corker of Tennessee, who is in line to become the top Republican on the Foreign Relations Committee, was more circumspect about Rice’s chances after his own meeting with the ambassador.

The GOP senator suggested that Obama “take a deep breath and nominate the person he really believes is the very best person for secretary of state, regardless of relationships.”

Corker, who traveled to Libya in early October, was highly critical of the administration and the intelligence community, saying that “the whole issue of Benghazi has been a tawdry affair.”

Democrats have rallied to defend Rice, casting the Republican criticism as political scapegoating.

“You know it’s a shame to create a sideshow that seems, I think, very clearly to be very political out of something that really has no bearing on what happened in Benghazi,” White House spokesman Jay Carney said Wednesday.

Rep. Adam Schiff, D-Calif., a member of the House Intelligence Committee, called the criticism a “transparent attempt” to deny Obama a potential Cabinet choice.

The issue remained at the forefront as the Senate, in debating a defense policy bill, approved an amendment by McCain that would lead to an increase of up to 1,000 Marine Corps personnel to provide security at U.S. diplomatic missions around the world.

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Associated Press writer Matthew Lee contributed to this report.

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