Obama challenges Republicans hammering Rice on Libya to 'go after me' President Obama aggressively challenged Republican senators threatening to block U.S. Ambassador to the U.N. Susan Rice if she is nominated for secretary of state, saying at a press conference Wednesday that those lawmakers seeking an "easy target" should just "go after me." At the same time, Obama appeared to acknowledge that Rice was far removed from the internal discussions over the attack when she was tapped to explain it on five Sunday talk shows. He described her as "a U.N. ambassador who had nothing to do with Benghazi." The full-throated defense of Rice follows weeks of criticism from Republicans concerned that she asserted repeatedly, five days after the Libya terror attack, that it was a "spontaneous" assault tied to an anti-Islam film -- despite evidence that it was a pre-planned terror attack. Amid speculation that Rice could be tapped to succeed Secretary of State Hillary Clinton, Sen. John McCain, R-Ariz., and others vowed to do "whatever is necessary" to block such a nomination. But Obama said Wednesday that Rice has done "exemplary work," and said "to besmirch her reputation is outrageous." "She made an appearance at the request of the White House in which she gave her best understanding of the intelligence that had been provided to her," Obama said. If Sen. McCain and Sen. (Lindsey) Graham and others want to go after somebody, they should go after me. He continued: "When they go after the U.N. ambassador apparently because they think she's an easy target, then they've got a problem with me." The president said he would nominate her if he thinks she is the best person for the job, but added "that's not a determination that I've made yet." Graham swiftly fired back. Mr. President, don't think for one minute I don't hold you ultimately responsible for Benghazi. I think you failed as Commander in Chief before, during, and after the attack," he said in a statement. We owe it to the American people and the victims of this attack to have full, fair hearings and accountability be assigned where appropriate. Given what I know now, I have no intention of promoting anyone who is up to their eyeballs in the Benghazi debacle. Other potential candidates for secretary of state include Sen. John Kerry. The chatter in Washington that Obama might instead go with Rice raised alarm among Republicans who have been repeatedly hammered her Sunday show appearances on Libya. Graham said Wednesday "I don't trust her." Obama also said Wednesday that it's "important" to find out exactly what happened in Benghazi and vowed to cooperate with Congress.