WASHINGTON Susan Rice's attempts to ease the concerns of her Republican critics seemed to have little effect on Wednesday, as more U.S. senators - including a moderate one-time supporter - raised new questions about her despite two days of meetings at the Capitol.
U.S. Senator Susan Collins met with the U.S. Ambassador to the United Nations for over an hour, over the September 11 attacks on the U.S. mission in Benghazi, Libya. Collins said afterward she could not back Rice for secretary of state, if she is nominated by President Barack Obama, without more information.
The moderate Republican even brought up a new concern, about Rice's record in the State Department 14 years ago in connection with the 1998 bombings of U.S. embassies in Africa.
Other Republicans have threatened to block Rice's nomination if Obama picks her to replace Secretary of State Hillary Clinton, which would require Senate confirmation.
Obama, who has strongly supported his embattled ambassador, gave a show of moral support on Wednesday, prompting applause from his Cabinet - including Clinton - during their first meeting at the White House since Obama's re-election on November 6.
"Susan Rice is extraordinary," Obama said, adding that he "couldn't be prouder of the job she's done."
Clinton told reporters later on Wednesday Rice had done a great job at the United Nations, and she hoped a board reviewing the Benghazi attack would complete their review shortly.
"They have been hard at work, we are hoping they will be finished with their work very soon," Clinton said.
Votes from moderates like Collins, who introduced Rice to the Senate Foreign Relations Committee when Obama nominated her to the U.N. post three years ago, would be needed to overcome procedural obstacles and win confirmation.
"I still have many questions that remain unanswered," Collins told reporters after a 75-minute meeting with Rice.
The top Republican on the Homeland Security Committee, Collins said she still wanted more information about the September 11 attack on the U.S. mission and a nearby CIA annex in Benghazi, Libya, in which the U.S. ambassador and three other Americans were killed.
The controversy raises the unpleasant specter of Obama starting his second term with a nasty confirmation fight. But he also risks looking weak if he seems to give in to criticism from the party he just defeated to win re-election.
Obama should nominate Rice if he feels she is the best choice, said Lawrence Korb, a former assistant secretary of defense now at the liberal Center for American Progress.
He predicted that she would win confirmation, given that the main objection to her was over a political point that defeated Republican candidate Mitt Romney tried to feature in his failed presidential campaign this year.
"The Republicans are desperate for an issue," Korb said. "She's not the issue. The issue is that they want to undermine his (foreign policy) narrative."
Sticking with Rice could also be a potent demonstration of strength for Obama, Korb said, reminiscent of Republican President Ronald Reagan. Reagan, who is revered by his party, won points for winning the confirmation of Al Haig as Secretary of State in 1981, despite objections over Haig's ties to the Watergate scandal, he noted.
Some observers have speculated that the Republicans would prefer Obama nominate Senator John Kerry, leaving the door open for a Republican to win his vacated Massachusetts seat and narrowing the Democratic majority in the Senate.
"I think John Kerry would be an excellent appointment and will be easily confirmed by his colleagues," Collins told reporters.
Collins stressed at length that the United States seems not to have learned lessons from the bombings of the embassies in Kenya and Tanzania in 1998, when Rice was the State Department's Africa region head.
This year's attack in Benghazi "echoed" those attacks, she said. "In both cases, the ambassador begged for additional security," and State turned down both requests, she said.
"I asked Ambassador Rice what her role was. She said that she would have to refresh her memory but that she was not involved directly in turning down the request. But surely, given her position as assistant secretary for African Affairs, she had to have been aware," Collins said.
Republicans have openly criticized Rice for initial comments after the Benghazi attack that suggested it was a spontaneous event arising from protests of an anti-Islam film rather than a planned terrorist strike.
Intelligence officials later said the attack was possibly tied to al Qaeda affiliates.
Republicans have argued that the Obama administration tried to play down the terrorist angle in its initial comments to avoid undermining the president's claims of success in fighting al Qaeda in the run-up to the November 6 election.
Rice, accompanied by acting CIA Director Michael Morell, also met with Senator Bob Corker, who is in line to be the top Republican on the Senate Foreign Relations Committee.
After his meeting, Corker had tough words for the Benghazi attack and the aftermath, which he termed a "tawdry affair," that would add to Americans' distrust of the government.
He declined to discuss whether he would support Rice, but urged Obama to "step back" from the controversy and "take a deep breath" as he decided whom to nominate.
Rice also met for about an hour behind closed doors on Tuesday with Republican Senators John McCain, Lindsey Graham and Kelly Ayotte, who have been among her most vocal critics.
(Additional reporting by Jeff Mason and Andrew Quinn, editing by Bill Trott and Todd Eastham)