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Secretary of State Hillary Clinton is scheduled to be on Capitol Hill Wednesday, to give long-awaited testimony about State Department security and the attack that left four Americans dead in Benghazi, Libya.

Clinton, who had to postpone testimony because of health issues, is scheduled to appear before the Senate Foreign Relations Committee at 9 a.m. and the House Foreign Affairs Committee at 2 p.m. Wednesday. She will be the only person giving testimony in the hearing called, "Terrorist Attack in Benghazi: The Secretary of State's View."

More than four months have passed since an act of terrorism killed U.S. Ambassador Christopher Stevens and three other Americans in Libya. Clinton was expected to testify about a report on security failures in Benghazi in December, but first a concussion and then a blood clot near her brain kept the out-going secretary of state away from Capitol Hill.

The report led to the firing of three State Department employees from their posts and one resignation because of "systemic failures and leadership deficiencies at senior levels in securing the compound." The departing staff are still on administrative leave, however, meaning they are still State department employees.

State Department spokeswoman Victoria Nuland said Clinton would first tell representatives at the morning hearing about how the department has begun implementing the report's recommendations.

"As she'll make clear tomorrow, all of the recommendations are currently being implemented, but there will be plenty of implementation work that needs to be carried forward by her successor," Nuland said at the daily briefing today.

Nuland also said Clinton has been reviewing recommendations from the Accountability Review Board, getting status updates on their implementation, and talking to people in the department who were pushing forward on the matter while she was out sick, all of which will be reflected in her prepared statements ahead of taking questions from members of Congress at both testimonies.

Clinton testified briefly before the Senate less than two weeks after the attack, but Sen. Mike Lee, R-Utah, said today that her testimony was full of "unsatisfying responses."

"We weren't getting answers to a lot of our questions," Lee told KSL Radio. "Some of that was understandable at the time because she didn't have all the information, but I'm curious to see what we'll hear from her."

Sen. John McCain, R-Ariz., was less understanding than Lee in September, saying Clinton told the Senate "nothing."

"We were told absolutely nothing, all because it's an investigation going on," McCain said on the Senate floor Friday, Sept. 21, 2012.

The hearing Wednesday is expected to focus on where State leadership went wrong and what can be done going forward, according to Rep. Ed Royce, chairman of the House Foreign Affairs Committee, who called it part of "an effort to ensure that nothing like [the Sept. 11, 2012 attack in Benghazi] happens again."

"It is important to learn all we can about what happened in Benghazi because at the end of the day, it could happen again," Royce said in a statement. "After all, al-Qaeda and associated groups plan to attack over and over again, as we saw most recently in Algeria."

Clinton spoke about efforts to combat terrorism in Algeria, which shares a border with Libya, following a meeting with Japanese Foreign Minister Fumio Kishida last week.

"It is absolutely essential that while we work to resolve this particular terrible situation, we continue to broaden and deepen our counter-terrorism cooperation," Clinton told reporters Friday. "We will not rest until we do as much as we can, alone and in concert with our partners, to restore security to this vital region and to bring those who would terrorize and kill innocent people to justice."

Sen. Robert Menendez, D-N.J., will preside over the hearing on the Senate side, in place of out-going SFRC chair Sen. John Kerry, D-Mass., whom President Obama has nominated to take over Clinton's position as secretary of State. Kerry's confirmation hearing before the SFRC begins Thursday.

ABC News' Dana Hughes contributed to this report.