South Dakota Gov. Kristi Noem traveled to Iowa to stump for former President Trump on Wednesday after saying Nikki Haley would be a "mistake" as Trump's running mate.

Noem, who endorsed Trump for president in September, was in Sioux City, Iowa, on Wednesday night and told potential Jan. 15 caucus voters that Trump is the best choice for Republicans.

"I’ve known the man for years now," Noem said onstage, according to KTIV, "worked with him when he was in the White House on tax cuts, worked with him on policies and trade agreements. I served on the Armed Services Committee, worked on foreign policy with him. He helped me build my economy in South Dakota."

Taking aim at Haley, who served as South Carolina governor and then as U.S. ambassador to the United Nations in the Trump administration, Noem told an audience, "She said that she was never going to run for president against President Trump, and now she's running for president against President Trump."

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"She defends him and then she attacks him. She defends you, she attacks you," Noem said of Haley, according to the Argus Leader. "Whichever way the political winds blow is where she goes, and we cannot trust our country to somebody like that either."

Touching on foreign policy, Noem added, "We would never have the situation going on like we see in the Middle East right now if he had been in the White House. We would never see what was going on with Russia and Ukraine. I mean, he would be strong, he’d be strong against North Korea."

Noem's visit comes before Trump is expected to campaign in Sioux Center, Iowa, on Friday.

The roughly 30-minute speech in Iowa came a day after Noem was asked on-air by Newsmax host Eric Bolling, "If he picked Nikki Haley, would that be a mistake?"

"Yes," Noem replied. "But if he picked her, I would tell him I disagreed with him. But then I would support the ticket because he’s still the president, and the president still makes the decisions and, you know, I just, I’ve had a lot of disagreements with Nikki Haley over the years. And I just don’t know which Nikki Haley is going to show up every day. She’s a different person, depending on whatever works for her political agenda."

Reached for comment Thursday, a spokesperson for Haley's campaign pointed to how Haley during an appearance on "Fox News Sunday" said she would not "play for second."

But in a Fox News Digital interview Tuesday, Haley did not categorically rule out being Trump's running mate.

During her speech in Sioux City on Wednesday, Noem also took aim at Florida Gov. Ron DeSantis, who has been endorsed for president by Iowa Gov. Kim Reynolds and visited all of the state’s 99 counties during a tour in which he touted how he defied mask and vaccine mandates in the Sunshine State, according to the Argus Leader. 

"We're not going to let people who run for office rewrite history," Noem said onstage Wednesday. "Ron DeSantis closed his businesses down. He closed his beaches down. When it was hard challenging political pressure in times when everything mattered and your constitutional freedoms were threatened, Ron DeSantis caved to pressure. And we just can't afford to put somebody as leader of the free world that caves to political pressure."

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Former Trump adviser Steve Bannon recently predicted a "big fight" will take place this spring over the direction of the Trump campaign. 

"They’re going to try to force Nikki on the ticket," Bannon said in an appearance on the podcast "Human Events with Jack Posobiec."

"They’ll say Trump needs a woman, Nikki, on the ticket, she balances things, and she can bring together that 15% of Never Trumpers in the Republican Party," Bannon said. "We’re going to have to have that fight. If Nikki Haley is in this administration in any capacity, it will fail. She’s a viper. She’s a viper, and once she gets in there, she’ll try to run it as prime minister. She’ll try to be Dick Cheney. Her to Trump will be just like Dick Cheney to Bush. That’s what she’ll try to do."

In an on-air interview with CBS News, Noem was asked if she was on the ground in Sioux City to audition for Trump’s vice presidential spot. She denied that was the case, saying, "I’m here to help the president win."

When pressed if she would accept an offer to run as Trump’s VP, Noem responded, "I think anybody in this country, if they were offered it, needs to consider it."

Noem also criticized Haley during the Wednesday appearance, saying, "I haven't supported Nikki Haley. I just think I don't really know who the real Nikki Haley is. She's whoever she needs to be for whatever ways the political winds blow that day."

"Nikki Haley would be a bad choice because I don’t know what she will say and do next," Noem said.