McCain said on NBC's "Today," quote, "I take on things ... when I believe they're wrong. Four Americans died that didn't have to die."
The Republican senator says he will block the nomination of U.N. Ambassador Susan Rice if she's tapped to replace Secretary of State Hillary Rodham Clinton.
McCain is angry about Rice's comments days after the attack on the U.S. embassy in Benghazi, which killed Ambassador Chris Stevens and three other Americans.
Rice attributed the attack to outrage in the Arab world over an anti-Muslim video, not to terrorism.
McCain said Thursday there was overwhelming evidence of the danger of an attack in Benghazi.