Sen. John McCain, R-Ariz., responded to President Obama’s challenge that he “go after me” over the Benghazi attack by  declaring him either incompetent or corrupt and suggesting he is not taking the attack seriously.

“This president — this administration — has either been guilty of colossal incompetence or been engaged in a coverup, neither of which is acceptable to the American people,” McCain said on the Senate floor today. “I speak as a friend of Christopher Stevens, I speak as a person who knows something about warfare, I speak as something of an authority — that this attack could have been prevented if the information on the ground had been taken into consideration.”

Stevens, the U.S. Ambassador to Libya, was killed during a terrorist attack on September 11, 2012, that the president and his team originally portrayed as an outburst that grew out of a protest against an anti-Islam Youtube video. Stevens and the U.S. mission to Libya repeatedly requested extra security as they faced 13 separate security threats in the lead-up to the attack, but those requests were denied.

McCain called for a congressional Select Committee to investigate the attack and the administration response. “There clearly is a need because there is a huge credibility gap among the American people because of the [contradictory statements about the attacks] beginning with the President of the United States,” McCain said. “What did the president know? When did he know about it? And what did he do about it?”

With that sequence of questions, Obama’s 2008 opponent echoed the question posed by Sen. Sam Baker, R-Tenn., during the Watergate investigation that brought down Richard Nixon.

McCain was responding to the “umbrage” that Obama took with his criticism of U.S. Ambassador to the United Nations Susan Rice, who did a round of Sunday talk shows promoting the idea that a Youtube video was the proximate cause of the attack.

“She gave her best understanding of the best intelligence that had been provided to him,” Obama said today in defense of Rice. “They should go after me, and I’m happy to have that discussion. But for them to go after the UN ambassador, who had nothing to do with Benghazi . . . to besmirch her reputation, is outrageous.”

McCain expressed shock at Obama’s counterattack. “He really does not have any idea of how serious this issue is. I’m a United States Senator,” McCain said. “We have our responsibilities, we have our duties, and we are not picking on anyone here.”

But he certainly blamed Obama for Rice’s performance. “Those talking points did not come from the CIA, they came from the White House,” he said.  “Who at the White House gave her those talking points?”