(CNN) -- She's mentioned by name only once in 85 pages, but former Secretary of State Hillary Clinton was back under a Republican microscope after a Senate report on the killings of four Americans in Libya.
"Sounds like the 2016 presidential race has now started," Sen. Dan Coats, R-Indiana, told CNN.
Clinton leads early polls of potential Democratic presidential contenders. GOP leaders quickly focused their fire on her after the Senate Intelligence Committee concluded that the 2012 assault on the U.S. diplomatic outpost in Benghazi was "likely preventable" based on known security shortfalls and prior warnings. U.S. Ambassador Chris Stevens, State Department computer specialist Sean Smith and security contractors Glen Doherty and Tyrone Woods were killed in that attack.
The Senate report spread the blame between the State Department and the intelligence community. State Department officials should have beefed up security in Libya's second-largest city because of general warnings that U.S. personnel were at risk. The intelligence community could have flagged potential threats on "extremist-affiliated social media," the report says. In addition, the report says intelligence officials inaccurately reported that a protest might have led to the attack, and took too long to correct the erroneous reports -- "which caused confusion and influenced the public statements of policymakers."
It follows a 2013 report by the State Department's Accountability Review Board, which resulted in the reassignment of four State Department officials.
But questions around security and intelligence as well as the changing explanation in the days that followed the attack -- which occurred in the heat of the 2012 presidential race -- led to allegations of a cover-up and repeated Republican calls for more explanation from the Obama administration. Wednesday's report did little to quiet them.
"It raises questions that I think need to be answered before we can put this to rest," said Coats, one of five Republicans who blasted Clinton in a statement of "additional views" tacked onto the end of the report -- the only part of the document that identifies her directly. They argued that as secretary of state, Clinton bore "ultimate accountability" for security at the Benghazi mission, "and we believe there should be a full examination of her role in these events, including on the night of the attacks."
"In this case, there are a lot of finger pointing elsewhere as to failures of the process and failures of the agency, et cetera," Coats said. "But no one really has stood up and said, 'I take responsibility for this.' That's important. The American people want justice done here and closure to this issue."
Clinton, who left office in February 2013, has said she accepts responsibility for the Benghazi deaths.
Speaking on condition of anonymity, a Clinton adviser told CNN, "Four Americans lost their lives. We have never and will never approach this tragedy through the prism of politics. If others continue to do so for their own gain, they're going to have to do it without us."
But Sen. Lindsey Graham, R-South Carolina, told CNN that Clinton "has to clear the air on Benghazi" if she wants to be president.
"She has a lot of accomplishments. She's a very accomplished woman. But, under her leadership, the consulate became a death trap," said Graham, who doesn't sit on the Intelligence Committee.
And Sen. John McCain, R-Arizona, said, "The American people hold all of us accountable who are in responsibility. She should be held accountable."
But comments like that drew a sharp response from the committee's chairwoman, California Democrat Dianne Feinstein, on Thursday. In a statement issued by her office, Feinstein said claims that the report blames Clinton for the Benghazi deaths are "patently false," and that the Republican addendum "unfairly criticizes Secretary Clinton."
Wednesday, Feinstein told CNN's The Situation Room that "it's interesting that the first thing out of the box is something that's political."
And at the White House, spokesman Jay Carney criticized what he called "a very politicized effort on this that has seen a lot of conspiracy theories floated, reported on as fact, and then debunked."
"Our interest is in getting those who are responsible, bringing them to justice, and taking the steps necessary to ensure that this kind of thing can't happen again or is far less likely to happen again," Carney said Thursday.
But efforts to bring the perpetrators -- identified as members of a variety of Islamic militant groups, some affiliated with al Qaeda -- to justice have been frustrated by the lack of "political incentive or will" by Libyan authorities to prosecute those believed responsible, the Senate report states. In addition, it noted, up to 15 people who had assisted the probe have been killed since September 2012, though it wasn't clear if the deaths were related to the probe.
CNN's Elise Labott and Paul Courson contributed to this report.