US Ambassador to the United Nations Susan Rice has conceded that an early account she gave about the attack on the US mission in Benghazi, Libya, was partly inaccurate.
However, her admission has failed to win over Republican senators, who accused her of misleading the public.
Ms Rice met Republican Senators John McCain, Lindsey Graham and Kelly Ayotte for about an hour behind closed doors.
They have threatened to block her nomination if US President Barack Obama chooses her for secretary of state or another top post in his new Cabinet.
They have criticised her for initial comments after the 11 September attack in Benghazi that suggested it was a spontaneous event arising from protests over an anti-Islam film rather than a premeditated attack.
The US ambassador to Libya and three other Americans were killed in the attack on the Benghazi mission and a nearby CIA annex. Intelligence officials later said the attack was possibly tied to al-Qaeda affiliates.
"We are significantly troubled by many of the answers that we got, and some that we didn't get, concerning evidence that was overwhelming leading up to the attack on our consulate," Mr McCain told reporters after the meeting.
"It is clear that the information that she gave the American people was incorrect when she said that it was a spontaneous demonstration triggered by a hateful video.
"It was not, and there was compelling evidence at the time that that was certainly not the case, including statements by Libyans as well as other Americans who are fully aware that people don't bring mortars and rocket-propelled grenades to spontaneous demonstrations."
Mr Graham said he would move to block the nomination of "anybody" who was linked to the Benghazi events.
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 6 November election.
Ms Rice, who was accompanied to the meeting by acting CIA Director Michael Morell, later issued a statement.
"We explained that the talking points provided by the intelligence community, and the initial assessment upon which they were based, were incorrect in a key respect: there was no protest or demonstration in Benghazi," she said.
"While, we certainly wish that we had had perfect information just days after the terrorist attack, as is often the case, the intelligence assessment has evolved.
"We stressed that neither I nor anyone else in the administration intended to mislead the American people at any stage in this process."
Ms Rice's controversial Benghazi statements were based on a set of unclassified talking points prepared by US intelligence agencies for members of Congress.
White House spokesman Jay Carney said yesterday that the questions about Ms Rice's appearance on the talk shows and the talking points she used had been answered.
"The focus on - some might say obsession on - comments made on Sunday shows seems to me and to many to be misplaced," he said.
However, Republican senators said the meeting with Ms Rice and Mr Morell left them with more concerns than before.
In a statement Mr McCain, Mr Graham and Ms Ayotte said there was now more confusion about who had made changes in the talking points before they were given to Ms Rice.