Former House Speaker Newt Gingrich is questioning whether Mitt Romney is tough enough to be secretary of state, given that the 2012 GOP nominee is now a serious contender for the job.

“Trump’s got to have somebody at state who’s very tough and very willing to take on foreign leaders,” Gingrich said on Fox News Tuesday night. “I can think of 20 other people who would be more naturally compatible with the Trump vision of foreign policy.”

Gingrich, who is advising Mr. Trump’s transition team, said Romney represents “a very different view point,” and cautioned that the president-elect “would have to really think through” the decision.

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“I’m not sure whose secretary of state he would be,” Gingrich said. “To what degree would Romney, once he became secretary of state, represent himself around the world, sort of in the John Kerry tradition...And to what extent would he actually represent the kind of tough-minded America-first policies that Trump has campaigned on.”

The former House speaker also brought up Romney’s opposition to Mr. Trump during the campaign, when he openly attacked Mr. Trump’s rhetoric and policy proposals, as another strike against him.

“I think the vast majority of Trump supporters will initially be very unhappy and will be reminded of the things Romney said,” Gingrich added.

Mike Huckabee, another Trump loyalist and former 2016 presidential candidate, also criticized Romney’s possible appointment.

“It’s not about that I don’t care for Mitt personally. But I’m still very unhappy that Mitt did everything he could to derail Donald Trump,” the former Arkansas governor said in another Fox News interview Wednesday. “He didn’t just go after him from the standpoint of ‘I disagree with his policy on immigration, I disagree with his policy on taxes.’ He attacked him on a personal level about his character, integrity, his honor.’”

Romney ripped into Mr. Trump during one speech in Salt Lake City earlier this year, where he called the then-GOP primary candidate “phony, a fraud” and “unfit” for the presidency. Mr. Trump fired back on Twitter at Romney, saying the 2012 presidential candidate “doesn’t know how to win.”

Huckabee said on Fox News that there was only one way Romney “could even be considered” for secretary of state: “He goes to a microphone in a very public place and repudiates everything he said in that famous Salt Lake City speech.”

The president-elect, who is also considering Rudy Giuliani for the top diplomatic post, met with Romney over the weekend in Bedminster, New Jersey, where the two spoke for more than an hour.

After the meeting Saturday, Romney spoke with reporters about his discussion with Trump: “We had a far-reaching conversation with regards to the various theaters in the world where there are interests of the United States of real significance.”