Small business owners, contract workers, freelancers and franchisees have kicked off a nationwide push to derail President Biden's nominee to head the Labor Department, beginning with a six-figure ad campaign in states where vulnerable Democratic senators are up for re-election in 2024.

The "Stand Against Su" is a coalition launched on Monday as the Senate prepares to consider Acting Labor Secretary Julie Su’s potential appointment to formally lead the department. Her critics cite her support for tightening employment regulations in California when she ran the state’s main labor agency, which they say makes her an enemy of both companies and employees.

"Simply put, Julie Su is anti-worker," the coalition said in a letter being circulated in an effort to drum up opposition to the nomination. "Her promotion to Secretary of Labor would cripple small business and eliminate job opportunities for millions of hard-working Americans."

The campaign will include billboard ads in Arizona, Maine, Montana and West Virginia, where moderates up for re-election next year have the potential to derail Su’s nomination in the Senate before she even gets a floor vote.

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Joe Biden and Julie Su

President Biden links arms with Julie Su, his nominee to be the next secretary of Labor at the White House, March 1, 2023. (Win McNamee/Getty Images)

A source familiar with the campaign told Fox News Digital of the cost, "For now it's in the low six figures, and it will continue to grow over time."

Senate Republicans have already successfully derailed two key Biden nominees with a boost from moderate Democrats, and are hoping to have the same success against Su. Federal Communications Commission (FCC) nominee Gigi Sohn withdrew from her confirmation process hours after Sen. Joe Manchin, D-W.Va., released a statement lambasting her prior progressive positions.

Federal Aviation Administration (FAA) nominee Phillip Washington similarly fell out of the running after Sen. Kyrsten Sinema, I-Ariz., reportedly scuttled his planned committee vote over worries about his lack of experience.

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Senator Joe Manchin

Sen. Joe Manchin was partially blamed for derailing Biden's FCC pick earlier this year. (Gaelen Morse/Bloomberg via Getty Images)

Sen. Bill Cassidy, R-La., the top Republican on the committee that’s set to grill Su during her confirmation hearing, signaled to Fox News Digital that some of Su’s biggest hurdles would be her support for California’s AB.5. That proposal was aimed at tightening restrictions on who employers could classify as an independent contractor.

Su's opponents also note that she supported what became known in the state as the "joint employer rule," which was designed to extend a franchisee operator's liability to the franchisor.

"Stand Against Su" is also hitting Su over the roughly $40 billion lost by way of fraudulent unemployment payments in California during COVID-19, and her advocacy against tipped minimum wage – which she previously called a legacy of slavery, according to the coalition.

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Marty Walsh and Joe Biden

Su would be replacing Marty Walsh, who left the administration to be a union leader (Demetrius Freeman/The Washington Post via Getty Images)

Two leading voices within the coalition called Su’s views a "nightmare."

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"As the chief enforcer of AB 5, Julie Su was a nightmare for freelancers and small businesses in California. She has no business being Labor Secretary after her track of failure," said Freelancers Against AB 5 founder Karen Anderson.

Wes Snyder, the owner of a FASTSIGNS franchise in Arizona, criticized Su’s stance on franchise liability.

"This business model gives anyone the opportunity to experience the transformative power of entrepreneurship while strengthening their local communities," he said. "Julie Su wants to rob us of this opportunity – she will turn the American dream into the American nightmare."