Sen. Ron Johnson (R-Wis.) made headlines this week for his heated confrontation with Secretary of State Hillary Clinton on Wednesday during her testimony before the Senate Foreign Relations Committee. Johnson alleged that the Obama administration had "purposefully misled" about the nature of the Benghazi, Libya, terrorist attack on Sept. 11, 2012 that killed Ambassador Chris Stevens and three other Americans.

But the 2010 Johnson disapproved of criticizing foreign policy publicly when there are troops in the field. "There's an appropriate way of opposing a policy and an inappropriate way," he told the Milwaukee Journal-Sentinel. "The appropriate way if I'm a U.S. senator is going to be not public. If I'm opposed to something, I'll make those views known very, very well, but privately with the administration." Johnson was running against then-Sen. Russ Feingold (D-Wis.), a vocal critic of the ongoing war in Afghanistan, and the quote was a shot at him for speaking out.

Johnson pressed Clinton on why the State Department couldn't immediately determine whether the attack had come out of a spontaneous protest over an anti-Islam video, as was initially reported, or a terrorist attack. He called one of Clinton's answers a "good excuse," to which Clinton replied, "Well no, that's a fact."

Clinton, exasperated by the repeated interruptions in the line of questioning, told Johnson, "With all due respect, the fact is we had four dead Americans. Was it because of a protest or was it because of guys out for a walk last night who decided to kill some Americans? What difference at this point does it make? It is our job to figure out what happened and do everything we can to prevent it from ever happening again, Senator."

Johnson said after the hearing that Clinton intentionally got emotional to avoid tough questions. "I think she just decided before she was going to describe emotionally the four dead Americans, the heroes, and use that as her trump card to get out of the questions. It was a good way of getting out of really having to respond to me," he told BuzzFeed.

Johnson walked back those comments on Thursday, saying he "probably speculated" about her emotions and shouldn't have.

He continued to discuss Benghazi Thursday during the Senate confirmation hearing for Clinton's likely successor, Sen. John Kerry (D-Mass.) Kerry called out Johnson for not attending a classified briefing on the attacks.

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  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya, during a hearing on Capitol Hill in Washington, D.C., on January 23, 2013. (SAUL LOEB/AFP/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee on Capitol Hill January 23, 2013 in Washington, D.C. (Photo by Chip Somodevilla/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya, during a hearing on Capitol Hill in Washington, D.C., on January 23, 2013. (SAUL LOEB/AFP/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee on Capitol Hill January 23, 2013 in Washington, D.C. (Photo by Alex Wong/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya, during a hearing on Capitol Hill in Washington, D.C., on January 23, 2013. (SAUL LOEB/AFP/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee on Capitol Hill January 23, 2013 in Washington, D.C. (Photo by Chip Somodevilla/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee on Capitol Hill January 23, 2013 in Washington, D.C. (Photo by Chip Somodevilla/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya, during a hearing on Capitol Hill in Washington, D.C., on January 23, 2013. (SAUL LOEB/AFP/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya, during a hearing on Capitol Hill in Washington, D.C., on January 23, 2013. (SAUL LOEB/AFP/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee on Capitol Hill January 23, 2013 in Washington, D.C. (Photo by Alex Wong/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya, during a hearing on Capitol Hill in Washington, D.C., on January 23, 2013. (SAUL LOEB/AFP/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya, during a hearing on Capitol Hill in Washington, D.C., on January 23, 2013. (SAUL LOEB/AFP/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee on Capitol Hill January 23, 2013 in Washington, D.C. (Photo by Alex Wong/Getty Images)

  • U.S. Secretary of State Hillary Clinton arrives to testify before the Senate Foreign Relations Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya, during a hearing on Capitol Hill in Washington, DC, on January 23, 2013. (SAUL LOEB/AFP/Getty Images)

  • U.S. Secretary of State Hillary Clinton arrives to testify before the Senate Foreign Relations Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya, during a hearing on Capitol Hill in Washington, D.C., on January 23, 2013. (SAUL LOEB/AFP/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya in the Hart Senate Office Building on January 23, 2013 on Capitol Hill in Washington, D.C. (MANDEL NGAN/AFP/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya, during a hearing on Capitol Hill in Washington, D.C., on January 23, 2013. (SAUL LOEB/AFP/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya, during a hearing on Capitol Hill in Washington, D.C., on January 23, 2013. (SAUL LOEB/AFP/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya, during a hearing on Capitol Hill in Washington, D.C., on January 23, 2013. (SAUL LOEB/AFP/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the Senate Foreign Relations Committee about the September 11 attacks against the U.S. mission in Benghazi, Libya, on Capitol Hill January 23, 2013 in Washington, D.C. (Photo by Alex Wong/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the House Foreign Affairs Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya in the Rayburn House Office Building on January 23, 2013 in Washington, D.C. (MANDEL NGAN/AFP/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the House Foreign Affairs Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya in the Rayburn House Office Building on January 23, 2013 in Washington, D.C. (MANDEL NGAN/AFP/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the House Foreign Affairs Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya in the Rayburn House Office Building on January 23, 2013 in Washington, D.C. (MANDEL NGAN/AFP/Getty Images)

  • U.S. Secretary of State Hillary Clinton is seated before testifying before the House Foreign Affairs Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya in the Rayburn House Office Building on January 23, 2013 in Washington, D.C. (MANDEL NGAN/AFP/Getty Images)

  • U.S. Secretary of State Hillary Clinton testifies before the House Foreign Affairs Committee on the September 11, 2012 attack on the U.S. mission in Benghazi, Libya in the Rayburn House Office Building on January 23, 2013 in Washington, D.C. (MANDEL NGAN/AFP/Getty Images)