In vintage contrarian style, Sen. Rand Paul’s big move in the presidential race is an anti-endorsement of Nikki Haley. And he’s considering whether to campaign against her as she gains steam in New Hampshire.

The Kentucky Republican criticized Haley’s foreign policy stances as those of the “Dick Cheney, John McCain wing of the party” in an interview on Friday morning and said she’s the only candidate the senator would not be comfortable with as the GOP nominee. Paul might even consider supporting independent candidate Robert Kennedy Jr. if Haley wins the nomination.

The libertarian-leaning senator is using his considerable national following to try and spike her candidacy. He calls himself “Never Nikki” and has launched a website criticizing her policy positions.

“The people who like the stuff that I’ve been doing need to be aware,” said Paul, who advocates cutting foreign aid and government spending overall. “I don’t want her to gain any traction without people knowing fully about her record.”

Paul’s unique position in the primary reflects his often lonely views on foreign policy and spending. And it it is a change of tactics for him to get involved at all. In recent interviews, he’s been studiously neutral on the GOP field.

But Haley’s rising poll numbers in New Hampshire and interest in the approaching early state contests helped motivate him to get involved.

Paul said it was a “possibility” that he will physically campaign against Haley or run ads against her. He said former New Jersey Gov. Chris Christie’s decision to drop out will likely benefit Haley and will make New Hampshire a tight race. So he decided this week “to make sure everybody knew where I stood anyway before the voting started.”

Paul ran for president himself in 2016, eventually endorsing Donald Trump and again supporting the former president in 2020. This time around Paul said he’d be comfortable if Trump, Florida Gov. Ron DeSantis or Vivek Ramaswamy won the nomination. And he put RFK Jr. in the mix too.

But on the issue of foreign policy, Paul said Haley’s stances are disqualifying, criticizing the former U.N. ambassador for her positions on Ukraine and foreign aid and warning she’s aligned with Republicans that might want to “bomb Tehran tomorrow.” Paul’s anti-interventionist streak more closely aligns with the other three candidates, who are skeptical of sending more money to Ukraine — something that Paul opposes entirely.

“I do like a lot of the aspects of at least three people on the Republican side as well as Bobby Kennedy. I’m absolutely dead certain Nikki Haley would be wrong for our country,” Paul said in the interview. “And I do have some voice. I want to make sure my voice is heard.”