WASHINGTON — A combative Secretary of State Hillary Rodham Clinton on Wednesday fended off fierce interrogations from senators and House members in congressional hearings illuminating the brutal Sept. 11 attack on the U.S. Consulate in Libya.Clinton, who testified before a Senate panel in the morning and a House panel later in the day, also promised to improve security for State Department officials in North Africa and around the world after the attack, which left a U.S. ambassador and three other Americans dead."I take responsibility,” she told the Senate Foreign Relations Committee. "Nobody is more committed to getting this right. I am  determined to leave the State Department and our country safer, stronger and more secure.”Clinton bristled at claims that the administration misled the public by initially linking the attack to a protest that spiraled out of control.Sen. Ron Johnson, R-Wis, said "a simple phone call” to people in Benghazi "would have established immediately” that there was no protest. "Why wasn’t that known?” he asked.Clinton said State Department officials decided it was not appropriate to talk to U.S. officials in Benghazi before the FBI conducted their interviews. Pressed further on why that call wasn’t made, Clinton erupted in anger."With all due respect ... what difference, at this point, does it make?” she said. "We have four dead Americans. It’s our job to figure out what happened and make sure it never happens again. ... People were trying in real time to get to the information.”Job No. 1, she said, is to find the killers and "bring them to justice.”Clinton, in what could be her last congressional testimony before leaving her post, said the deaths were "personal” for her.She was near tears as she talked of standing next to President Barack Obama "as the Marines carried those flag-draped caskets off the plane at Andrews (Air Force Base). I put my arms around the mothers and fathers, sisters and brothers, sons and daughters.”Sen. John McCain, R-Ariz., gave Clinton a warm but brief welcome before quickly pressing her on security issues at the consulate. He said when he met with U.S. Ambassador Christopher Stevens on July 7 — more than two months before the attack — Stevens expressed "his deep and grave concerns about security in Benghazi and the need for additional assistance.”Clinton said requests for more security never reached her desk. McCain said the administration’s "preference for a ‘soft footprint’ was part of the reason for what took place” in Benghazi.