Democratic presidential frontrunner Hillary Clinton faces a congressional grilling Thursday over her role during and after the deadly attacks on the US mission in Benghazi, a hearing one top Democrat blasted as a "political hit job."
Clinton, who served as President Barack Obama's first secretary of state from 2009 to 2013, will make her highly-anticipated public appearance before the House committed tasked with investigating the 2012 attacks that left four Americans dead.
If she performs well, Clinton could convince skeptical voters that it is time to move on from the controversy that has dogged her presidential campaign and address issues such as how to improve the US economy and address foreign policy challenges.
Should her testimony raise more questions than it answers, Clinton could face a heightened barrage of Republican attacks during the 13-month run up to the November 2016 election.
The Benghazi committee has been deeply controversial, and in recent weeks GOP lawmakers including the number two Republican in the House, Kevin McCarthy, suggested that the panel served to help damage Clinton's standing in the presidential race.
The murky events of September 11, 2012 began when Islamist extremists attacked and ransacked a US diplomatic compound in Benghazi.
Ambassador Christopher Stevens is believed to have sought shelter in a safe room in the compound. His lifeless body was located at a local hospital that night, the first killing of a US ambassador since 1979.
Another American died at the compound, while two more died in a subsequent mortar attack.
Congress conducted seven probes into the attack, and Clinton launched an Accountability Review Board to investigate the events.
The board's report did not fault the State Department for the terror attacks but cited "systemic failures and leadership and management deficiencies at senior levels" that resulted in an inadequate security posture.
Several Democrats rushed to Clinton's defense Wednesday in anticipation of her testimony.
"In recent weeks, it's become absolutely clear that this committee is nothing more than a political hit job on Hillary Clinton," Senate Democratic Leader Harry Reid told his colleagues.
"They said be ready for eight hours of interrogation. And that's what this is, interrogation."
The Benghazi tragedy has hovered over Clinton for three years, threatening to upend her presidential candidacy especially after the committee's investigation led to the revelation that Clinton used a homebrew email account and server during her tenure as America's top diplomat.
Democrats have debated whether Clinton was a wounded candidate made vulnerable by the Benghazi probe, considerations that no doubt reached Vice President Joe Biden as he mulled his own White House run.
But Biden's announcement Wednesday that he will not seek the presidency likely eased pressure on Clinton less than 24 hours before her appearance before the House Select Committee on Benghazi, beginning at 10:00 am (1400 GMT).
Democrats have called for the committee's abolition, arguing it has cost taxpayers nearly $5 million and dragged on far too long.
They seized on McCarthy's remarks, and those of Republican congressman Richard Hanna who said the committee was "designed to go after" Clinton, as evidence the panel seeks to sabotage her presidential bid.
An exasperated committee chairman Trey Gowdy on Sunday urged his fellow Republicans to "shut up" about the probe because most of them do not know the details of the investigation.
On Sunday, Gowdy assured that the committee is "not investigating Secretary Clinton" or allegations of how she handled classified information, but the events of 2012 and the decisions made before, during and after the attacks.
Republican committee member Mike Pompeo said he expected Clinton would be asked about whom she contacted on the night of the attack.
"I expect we'll have many questions about who acted, who spoke and why it was the case that the response was insufficient to address the needs of the men on the ground," Pompeo told Fox News Tuesday.
Senator Dianne Feinstein, who chaired the Senate Intelligence Committee when it conducted a bipartisan review, recalled how that 16-month investigation "found no wrongdoing" by Clinton and earned unanimous support in committee.
"I'm appalled that House Republicans are wasting time and money in an effort to disparage Secretary Clinton," Feinstein said.