Sen. Rand Paul (R-KY) opposes the nomination of two of Donald Trump’s reported top choices for secretary of state: former New York City mayor Rudy Giuliani and former U.N. ambassador John Bolton.

“It’s important that someone who was an unrepentant advocate for the Iraq War, who didn’t learn the lessons of the Iraq War, shouldn’t be the secretary of state for a president who says Iraq was a big lesson,” Paul told the Washington Post in a Tuesday interview. “Trump said that a thousand times. It would be a huge mistake for him to give over his foreign policy to someone who [supported the war]. I mean, you could not find more unrepentant advocates of regime change.”

The libertarian Kentucky senator said that Trump should stick to the “America first” campaign policy that he trumpeted on the campaign trail and select an appointee opposed to U.S. military intervention abroad.

As a member of the Senate Foreign Relations Committee, Paul will be able to vote on whether he recommends Trump’s nominee for secretary of state. The November election gave Republicans a 10-to-9 majority on the committee, meaning that Paul’s vote against Trump’s choice could be decisive. The secretary of state nomination would still be put to a full Senate vote, but Paul’s opposition would cast a pall.

Paul has been a vocal critic of the 2003 U.S. invasion of Iraq for years, referring to it as a “mistake.”

“I’m hoping that if there’s a public discussion of this before it happens, people in the incoming administration realize that regime change made us less safe and the Iraq War made us less safe,” Paul told the Post. “We don’t need, as our chief diplomat, someone whose idea of diplomacy is dropping bombs.”

He recommended a nominee like Senate Foreign Relations Chairman Bob Corker (R-TN) and urged Trump not to go near neo-conservative secretary of state prospects “with a ten-foot pole.”