As Obama’s longest-serving foreign policy adviser, Susan Rice, 47, is reportedly under consideration to succeed Secretary of State Hillary Rodham Clinton. (Stephen Chernin — AFP/Getty Images)

President Obama strongly defended U.N. Ambassador Susan Rice against attacks Wednesday by a trio of Republican senators who said she is ill-qualified to serve as secretary of state because of how she explained the roots of the Sept. 11 attack on the U.S. consulate in Benghazi, Libya.

Bristling with evident indignation during a news conference, Obama said Rice has “done exemplary work” with “skill, professionalism and toughness and grace.”

He then made a pointedly and almost personal challenge to Sens. John McCain (R-Ariz.), Lindsey Graham (R-S.C.) and Kelly Ayotte (R-N.H.) who earlier Wednesday said Rice is unqualified to lead the State Department because she appeared either misinformed or ill-prepared to discuss the attack on the U.S. diplomatic post in Benghazi,  on national political talk shows a few days after the attack.

“If Sen. McCain and Sen. Graham and others want to go after somebody they should go after me,” Obama said. “For them to go after the UN ambassador who had nothing to do with Benghazi…to besmirch her reputation is outrageous.”

Obama said he hasn’t made any final decisions on who to nominate to Cabinet posts in his second term, but said that he would not hesitate to nominate Rice even in the face of Republican opposition.

Graham responded to Obama’s comments by e-mail just as the press conference concluded. “Mr. President, don’t think for one minute I don’t hold you ultimately responsible for Benghazi,” Graham said in a statement. “I think you failed as Commander in Chief before, during, and after the attack.”

Graham joined with McCain and Ayotte Wednesday to call for Watergate-style hearings on the Libya attack, while also saying they would block Rice’s nomination, if it occurs.

“I am dead-set on making sure that we don’t promote anybody who was an essential player in the Benghazi debacle,” Graham told reporters.

McCain added later that they would not rule out mounting a filibuster of the nomination.

Obama is reportedly considering Rice to succeed Secretary of State Hillary Rodham Clinton as head of the State Department as part of a series of moves that might also send Sen. John F. Kerry (D-Mass.) to lead the Pentagon. Rice, 47, served as an adviser to Obama’s 2008 presidential campaign and was later tapped to represent the United States at U.N. headquarters in New York. Rice makes few television appearances to discuss the administration’s foreign policy, but she appeared on all five major-network Sunday morning political talk shows less than a week after the Benghazi attack.

During those interviews, Rice said that the attack grew out of a spontaneous demonstration against an anti-Muslim video. But reports from the ground and statements by administration officials since Rice’s comments have varied

Graham was especially critical of Rice on Wednesday and said her comments on the shows were “so disconnected to reality, I don’t trust her. And the reason I don’t trust her is because I think she knew better, and if she didn’t know better, she shouldn’t be the voice of America. Somebody has got to start paying a price around this place.”

Ayotte agreed: “You don’t end up on every single major Sunday show without affirmatively putting yourself out there of wanting to carry forward a message on behalf of the administration. I think that there’s a certain responsibility with the current position that she has to ask proper questions about what we did and didn’t know at that point before she affirmatively puts herself out there on every major network to communicate to the American people.”

The senators said they want a special joint committee to investigate the attack and hear testimony from the administration’s top national security officials, including former CIA director David Petraeus, because separate ongoing investigations by the Senate’s armed services, foreign relations and intelligence committees will only yield partial information.

“The three committees will not be able to hear what the other groups are saying,” Graham said. “I’d like to ask Gen.Petraeus some questions, and I’m sure there are some people on the [Intelligence Committee] that would like to hear what the Department of Defense has to say about their handling of the Benghazi attack. And when it comes to the State Department, all of us would like to know, why were there so many requests for additional security denied.”

“If you have these people in separate rooms, telling separate stories, trying to blame each other, it’s going to fall through the cracks,” Graham added.

But Senate Majority Leader Harry M. Reid (D-Nev.) said Wednesday that he would not bring the senators’ resolution up for a vote. And Senate Intelligence Committee Chairman Dianne Feinstein (D-Calif.) also said Wednesday that she wouldn’t support establishing a select committee: “We’re doing our inquiry, that’s already underway.”

In his remarks, Obama also denied that the military or CIA held back any assets or effort in attempts to rescue the Americans under attack. “My orders to my national security team were to do whatever we need to do to make sure they are safe,” Obama said.

Greg Miller contributed to this report.

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