An outraged President Barack Obama accused Republicans, including John McCain, of besmirching UN envoy Susan Rice, re-igniting a fierce row over the slaying of the US ambassador to Libya.
Obama threw the weight of his replenished political capital behind Rice, the favorite to be his next secretary of state, as Republicans, lined her up as a top administration scalp over the attack in Benghazi on September 11.
McCain and his ally Republican Senator Lindsey Graham had earlier demanded "Watergate-style" hearings about what happened in Libya on September 11, and vowed to thwart any attempt to make Rice America's top diplomat.
"If Senator McCain and Senator Graham, and others want to go after somebody they should go after me," Obama declared, his eyes flashing real anger as he held his first press conference since being re-elected last week.
"But when they go after the UN ambassador, apparently because they think she's an easy target, then they've got a problem with me," Obama said.
"To besmirch her reputation is outrageous," Obama said, adding that if he decided that Rice was the best candidate to succeed Hillary Clinton at the State Department, he would go ahead and pick her.
Republicans have singled out Rice because she went on Sunday political talk shows in the wake of the Benghazi attack and said it was the "best assessment" of the US government that the strike was not pre-planned.
Rice said the assault, which killed US ambassador Chris Stevens and three other Americans, appeared to be a "spontaneous" reaction to a raid on the US embassy in Cairo by extremists and an anti-Muslim video made on US soil.
The Obama administration subsequently admitted that the attack was carried out by militants linked to Al-Qaeda, and State Department and FBI probes are currently under way to find out what happened.
Graham, a hawkish Republican keen to prevent any primary challenge from his right in the 2014 mid-term elections, swiftly responded to Obama's remarks.
"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."
Earlier, at a press conference Graham fumed "somebody has got to start paying a price around this place."
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"I don't think she deserves to be promoted. I am dead set on making sure we don't promote anybody that was an essential player in the Benghazi debacle."
For Republican hawks, Rice's attitude was proof the administration was oblivious to threats that existed in Benghazi, wanted to downplay evidence of a terror strike, and deserted Americans as they died on foreign soil.
The new row over Benghazi came as political temperatures mounted ahead of a series of hearings on the attack in Congress, and was a sign that elections, however decisive, rarely still the political tempest in Washington for long.
McCain insisted he was "not picking on anyone," as he took a dig on the "pretty good" life Rice leads as UN ambassador in an interview on FoxNews aired late Wednesday.
"You know, it is not a bad life being ambassador to the UN. You have a nice suite in the Waldorf Astoria," he said.
But he added, ultimately, he is "holding the president of the United States responsible."
"We want answers and the buck does stop at your desk, Mr. President," he said.
Earlier Wednesday, McCain gave notice that Rice would face a tough confirmation battle in the Senate, where minority Republicans could filibuster her nomination if she is promoted.
"I will do everything in my power to block her from being the United States Secretary of State," Republican Senator John McCain said on Fox News Wednesday.
"She went out and told the American people something that was patently false and defied common sense," he said.
Obama however said that Rice, who would be America's second African American secretary of state and has been a close ally of the president for years, had given her "best understanding" of the intelligence at the time.
The showdown raised the prospect that Obama could be forced to spend some of his new political leverage on a prolonged showdown over a Rice nomination with Congress -- even as he duels with Republicans over a "fiscal cliff" debt and spending crisis.
Later in the press conference, in the East Room of the White House, Obama declined to directly answer a question over whether he had given an order to launch a direct military rescue operation in Benghazi.
"My orders to my national security team were -- do whatever we need to do to make sure they're safe," he said.
"That's the same order that I would give anytime that I see Americans are in danger, whether they're civilian or military, because that's our number one priority."
The US military has said that there was no time to move assets into position sufficiently quickly to mount action around the consulate.