Secretary of State Hillary Clinton, in one of her final duties as the nation’s top diplomat, has told Congress her agency is moving ahead to improve security at U.S. diplomatic missions abroad, following the September attacks in Benghazi, Libya, that killed four Americans.

Clinton, during her first testimony before the Senate Foreign Relations Committee on Wednesday, said she is committed to leaving the department and country "safer, stronger and more secure." Clinton will appear before the House Foreign Affairs Committee in the afternoon, in what could potentially be her last appearance on Capitol Hill as secretary of state before transferring the job to U.S. Sen. John Kerry, D-Mass. Kerry’s nomination hearing is Thursday.

Congressional Republicans have been vying to have Clinton answer for the Sept. 11, 2012, attack that killed a U.S. ambassador and three other Americans. They are expected to question Clinton about the Obama administration’s varied explanations for the unexpected attack, which some conservatives have suggested are indicative of a cover-up.

Clinton, addressing in a prepared statement Republican criticisms of the administration’s initial response to the attacks, told the Senate panel that she stood with President Barack Obama that day when he described the event as an “act of terror,” the Washington Post reports. She has previously taken full responsibility for the findings of a bipartisan Accountability Review Board report that criticized the State Department's "systematic failures and management deficiencies."

Clinton said a department task force examined the Review Board's recommendations and translated them into 64 specific "action items," most of which are expected to be completed by the end of March.

State Department spokeswoman Victoria Nuland said Tuesday that Clinton will “answer any questions they [Congress] have of her” and will make clear that “all of the recommendations are currently being implemented.”

Clinton is widely considered to be the leading contender for the 2016 Democratic presidential nomination, despite regularly brushing off questions and speculation about her political future. She returned to work earlier this month after an unexpected sick leave and hospitalization for a blood clot in the head, the product of a fall.

However her husband – and former President – Bill Clinton has been less enigmatic. During a recent conference of the Clinton Foundation, Clinton said he didn’t rule out another presidential run for his wife if she “thinks this is the right thing for her and for America and for the world.”