Establishment Republicans and a right-wing group of former spies and special forces operatives that says it is nonpartisan but has historical Republican ties are raising a ruckus over Hillary Rodham Clinton's handling of the 2012 assault on US installations in Benghazi, Libya.
The criticism of Clinton over the deadly attacks appears to be a preview of what the former secretary of state can expect should she pursue a presidential bid in 2016.
Four Americans, including US Ambassador Chris Stevens, were killed on September 11, 2012, in assaults by suspected militants on the lightly guarded US diplomatic post in Benghazi and a better-fortified CIA installation nearby.
The report of an official State Department review board, released in December 2012, found that security at Benghazi was grossly inadequate and cited leadership deficiencies at two department bureaus. It did not fault Clinton herself.
But Republican critics are not buying their assessment.
The Republican National Committee has condemned Clinton's performance, suggesting in a recent research paper that "Benghazi is still the defining moment of Clinton's tenure as Secretary of State."
A new "Investigation of Benghazi" page on the website of Republicans in the US House of Representatives says the White House "still refuses to tell the whole truth" in the face of a year of exhaustive investigation by House committees.
At the same time, more personal accusations have been laid against Clinton by OPSEC (military slang for "operational security"), a group of former special forces and intelligence operatives that first surfaced during the 2012 presidential campaign.
"If Hillary Clinton wants to run for president she's not going to be able to continue hiding from the fact that she did nothing to help prevent the deaths of four Americans in Benghazi," said Scott Taylor, president of OPSEC, which this week is publishing a report highly critical of her actions during the Libya event.
The group charges Clinton with failing to ask the Pentagon and spy agencies to help US personnel besieged in Benghazi and with not discussing the attack with President Barack Obama until more than six hours after it started. They also say she was not candid in her own accounts of what happened.
But Clinton aides and a retired senior US diplomat who led a review of the Benghazi events say the new efforts are little more than political theatre.
Thomas Pickering, who chaired the State Department's official inquiry, said his panel concluded Clinton's performance was appropriate: "We did look at her role. We thought that she conducted her meetings and activities responsibly and well."
Republican censure of Mrs. Clinton is expected to intensify, even though it is unusual to see such fierce, coordinated opposition to a would-be presidential candidate surface 2-1/2 years before nominating conventions.
Some House Republicans have even begun a campaign, perhaps with Clinton in mind, to set up a "select committee" to investigate the administration's management of Benghazi. As of Monday, the bill had more than 180 cosponsors.
OPSEC is reentering the fray with gusto. Two years ago, it organised a media campaign - including a 22-minute film and TV ads - accusing Obama of seeking political gain from the May 2011 military operation that killed Osama bin Laden.
This week the group is scheduled to publish the 20-page report saying Hillary Clinton was "unsupportive" and "unaccountable" in her oversight of initial US efforts to mitigate the attack and in her responses to congressional and other official inquiries into the event.
The report, entitled "Breach of Duty: Hillary Clinton and Catastrophic Failure in Benghazi," says that due to a lack of due diligence by Congress, the "full story about Hillary Clinton's deadly failure of leadership may never be completely told." It calls for a special congressional investigation of the affair.
Close Clinton adviser Phillipe Reines declined request for comment, pointing instead to a TV interview in which he said Clinton believed that US diplomats had to operate in potentially dangerous places like Benghazi.
Clinton, Reines said then, was "proud of what she has done to ... handle and to improve and to try to prevent" a repetition of a Benghazi-type incident. "And I would think that, again, in the context of trying to be constructive to prevent this from happening again, which is the most important thing, is not to make it a political football."
Pickering condemned the way the Benghazi incident was being politicised: "Our investigation was certainly independent, thoroughly researched, carefully presented." He said the new round of accusations appears to be "clearly an effort to introduce once again partisan politics into an issue which should be furthest from partisan politics."
Fred Rustmann, a former CIA official who has spoken on OPSEC's behalf, said the group is "not affiliated in any way with the Democrat, Republican or any other party."
However, in August 2012 Reuters reported that key figures involved with OPSEC's campaign critiquing Obama included individuals with current or former affiliations with national and local Republican Party organisations.
While OPSEC's Taylor recently won election as a Republican member of Virginia's House of Delegates, the group has no relationship with any political party, a source close to OPSEC said.
Federal tax filings show that the group's revenue in 2012 was $1.8m. Most of OPSEC's funding today comes from small donations, Taylor said.
OPSEC's 2012 tax return also shows that in 2012 the group raised more than a quarter of its funding through Internet and mail campaigns run by Campaign Solutions, a political consultancy based in Alexandria, Virginia, which says on its website that it represents "Republican candidates from State House to White House."