Hillary Clinton has stood her ground through a gruelling day of questioning over the 2012 Benghazi attacks, at a high-stakes congressional hearing that could affect her bid for the White House.
Partisan fireworks exploded repeatedly between Republican and Democrat members of the House select committee on Benghazi.
But the Democratic frontrunner for president was relentlessly composed as she accused her rivals of exploiting the deadly attacks in Libya for political gain.
In more than six hours of highly-anticipated testimony, broadcast live across US television networks on Thursday, Clinton accepted, as she has done in the past, her share of blame for the attack which cost the lives of four Americans including ambassador Christopher Stevens.
"I take responsibility for what happened in Benghazi," she said. "I'm here to honour the service of those four men."
But she firmly rebutted charges she failed to boost security at the US diplomatic compound overrun by Islamist extremists on September 11, 2012, saying she was never consulted directly about requests for additional measures.
Clinton also stressed the need for the US to accept risks as it pursues its vital interests in a dangerous world, and to acknowledge that it can "never prevent every act of terrorism or achieve perfect security."
The Benghazi tragedy has hovered over Clinton for three years, threatening to upend her White House candidacy especially after the inquiry launched 17 months ago led to revelations that she used a homebrew email account and server while she was the country's top diplomat.
A strong performance at the Benghazi hearing could help Clinton convince sceptical voters that it is time to move on from the controversy that has dogged her campaign.
But should she stumble, she could face a heightened barrage of attacks on her judgment and diplomatic acumen during the run up to the November 2016 election.
There were several sharp exchanges with Republicans, including over the way the administration first publicly characterised the attack - which came weeks before the 2012 presidential election - as a spontaneous reaction to an anti-Muslim video.
"Libya was supposed to be... this great success story for the Obama White House and the Clinton State Department," as they highlighted global security gains since Obama took office, conservative congressman Jim Jordan said in a fiery critique.
"You can live with the protest about a video. That won't hurt you. But a terrorist attack will," he said.
"Where did the false narrative start?" Jordan asked.
"It started with you, Madam Secretary."
Clinton rejected the accusation, shooting back at Jordan: "I'm sorry that it doesn't fit your narrative, congressman."
Several Republicans questioned Clinton about Sidney Blumenthal, a longtime friend and former Bill Clinton aide, and his direct access to her.
Gowdy at one point entered a shouting match with Democrats over whether to release the full transcript of Blumenthal emails with Clinton and aides.
The exchange prompted Clinton's campaign chairman John Podesta to post on Twitter: "After 17 months and $4.7 million spent, their whole argument is about Sid Blumenthal?"
The US Congress has conducted seven probes into the Benghazi attack, and Clinton launched an Accountability Review Board to investigate the events.
The board's report did not fault the State Department but cited "systemic failures and leadership and management deficiencies at senior levels" that resulted in inadequate security.
Critics have pointed to the department's rebuff of requests for additional US security measures in Libya, left unstable after strongman Muammar Gaddafi's ouster.
Clinton insisted such requests, or rejection of requests, rarely reached her desk.