* Secretary of State sidelined by illness
* Clinton testimony on Libya likely in January
* Conservative critic suggests case of "Benghazi flu"
By Andrew Quinn
WASHINGTON, Dec 20 (Reuters) - U.S. Secretary of State Hillary Clinton is not known for avoiding controversy.
But as Washington reviews an independent inquiry that slammed Clinton's State Department for failures related to the fatal September attack on the U.S. diplomatic outpost in Benghazi, Libya, Clinton herself remains sidelined by illness and out of the public eye.
"All of you who know Hillary know that she would rather be here today," Senate Foreign Relations Committee chairman John Kerry - tipped as Clinton's likely replacement to head the State Department when she steps down next month - told a hearing on Thursday devoted to the Benghazi attack.
"I know how deeply she feels the importance of the discussion that we're having today, and I assure you it is not her choice that she is not here today and she looks forward to appearing before the committee in January."
Clinton, one of President Barack Obama's most popular and most visible Cabinet secretaries, frequently mentioned as a potential 2016 Democratic presidential contender, suffered a concussion last week in a fall due to dehydration caused by a stomach virus, doctors say.
Clinton's illness has removed her from the spotlight during discussion of the inquiry into Benghazi, where militants stormed the U.S. mission on the anniversary of the Sept. 11, 2001 attacks on New York and Washington, killing U.S. Ambassador Christopher Stevens and three other Americans.
The attack - the first to kill a U.S. ambassador in the line of duty since 1979 - has sparked criticism of her State Department, and the inquiry found widespread failures in both security planning and internal management.
The report did not find Clinton personally responsible for any security failures, and she accepted overall responsibility for Benghazi and the safety and security of U.S. diplomats overseas.
But official repercussions appeared limited to four mid-level State Department employees, including its top security officer, who resigned under pressure this week. The other three were relieved of their duties in the department's Diplomatic Security and Near Eastern Affairs bureaus.
Clinton, who officials say is working from home, released a letter this week to lawmakers in which she accepted the conclusions of the inquiry and outlined steps the State Department is taking to address the shortcomings it identified.
SURROGATES UNDER FIRE
But critics say Clinton has left much of the public explanation of Benghazi to surrogates such as U.S. Ambassador to the United Nations Susan Rice. It was Rice, not Clinton, who went on five television talk shows on Sept. 16, the Sunday after the attack, and said it appeared to be the result of a spontaneous demonstration rather than a planned assault.
There was no protest, it turned out, and Rice was blasted by Republicans for months. She became a political casualty of the incident, withdrawing last week from consideration as Obama's secretary of state.
Republicans, who cross-examined Clinton's top two deputies at Thursday's hearings, have said they still look forward to the chance to grill Clinton herself before she steps down next month at the start of Obama's second term.
"I think it's imperative that she come before this committee," Senator Bob Corker said at Thursday's hearing.
"I think it would be really a shame to turn the page on this, and go to a new regime, without her being here. So I do look forward to that happening whenever her health permits."
A handful of conservative firebrands have gone so far to suggest that Clinton's absence this week may be a convenient way to avoid the Benghazi hotseat.
"I'm not a doctor, but it seems as though the secretary of state has come down with a case of Benghazi flu," Republican Rep. Allen West, who lost his bid for re-election in November, told Fox News on Thursday.
State Department spokeswoman Victoria Nuland this week rejected "wild speculation based on no information."
"On doctor's orders, she is working at home this week. That's all we've got going on," she said.
Some Democrats have come out fighting, saying insinuations that Clinton has not fully shouldered responsibility over Benghazi were part of a broader partisan effort to attack the administration.
Outgoing Democratic Rep. Gary Ackerman reacted angrily on Thursday after Republicans on the House Foreign Affairs Committee said Clinton's State Department should not ask for more security funds while it wastes money on "global climate change, culinary diplomacy programs and other favored projects".
"Derogatorily looking at the secretary of state, who has worked herself to the bone - to the point of dehydration and exhaustion - as traversing the globe and teaching cooking classes or some nonsense rather than doing things that are serious does a disservice," Ackerman said.
"Certainly she's a qualified individual who can both cook and talk policy at the same time."