• Texas Attorney General Ken Paxton filed a petition for review in the U.S. 5th Circuit Court of Appeals challenging the validity of the administration's mandate.
• Paxton said he would soon file a motion asking the court to halt the mandate.
• The Labor Department's top legal advisor, Seema Nanda, said in a statement Friday that the Biden administration is "fully prepared to defend this standard in court."

Texas challenged the Biden administration on Friday over its Covid vaccine mandate for private businesses, arguing that the new federal requirements are unconstitutional.

State Attorney General Ken Paxton filed a petition for review with the U.S. 5th Circuit Court of Appeals challenging the validity of the administration's mandate. Paxton said he would soon file a motion asking the court to halt the mandate.

Paxton, in a statement, called the vaccine mandate "a breathtaking abuse of federal power" that is "flatly unconstitutional." He argued the mandate goes beyond the "limited power and specific responsibilities" of the Occupational Safety and Health Administration, which announced the new workplace regulations earlier this week.

The attorney generals of Louisiana, Mississippi, South Carolina and Utah joined the petition, in addition to several companies.

OSHA, which polices workplace safety for the Labor Department, developed the vaccine mandate under emergency authority that allows the agency to shortcut the normal process to issue new worker safety standards, which often takes years.

The Labor Department's top lawyer, Seema Nanda, said in a statement Friday that the Biden administration is "fully prepared to defend this standard in court."

"The Occupational Safety and Health Act explicitly gives OSHA the authority to act quickly in an emergency where the agency finds that workers are subjected to a grave danger and a new standard is necessary to protect them," said Nanda, the Labor Department's solicitor.

Nanda said the emergency safety standard "preempts any state or local requirements that ban or limit an employer's authority to require vaccination, face covering, or testing."

Texas Gov. Greg Abbott banned vaccine mandates through an executive order last month. Abbott had asked the state legislature to replace his order with a law, but the legislation failed to gain traction with lawmakers after several business groups opposed the state ban on vaccine mandates.

Abbott also barred local governments from requiring people to wear masks through an executive order in May. Several school districts sued Abbott over that order.

"The question that we always have and that we ask to the Republicans is: Why are they getting in the way?  Why are they getting in the way of trying to protect and save lives? That's all we're trying to do," White House deputy press secretary Karine Jean-Pierre told reporters Thursday.

The vaccine mandate, which applies to businesses with 100 or more employees, took effect Friday after publication in the Federal Register.

The mandate requires businesses to ensure their employees have received their vaccine shots by Jan. 4, or submit a negative Covid test at least once a week. Unvaccinated workers have to start wearing masks indoors by Dec. 5. The mandates covers 84 million private sector employees.

Paxton and nearly every other Republican attorney general in the U.S. threatened to use "every available legal option" to halt the mandate in a letter to President Joe Biden in September.

Republicans and some industry lobbyists have contended that the current threat from Covid does not amount to a grave danger as the Biden administration has said. They point to the growing level of vaccination and natural immunity in the U.S. from previous infections as well as mitigation measures already taken by many businesses in the workplace. 

"A virus that has killed more than 745,000 Americans with more than 70,000 new cases per day currently is clearly a health hazard that poses a grave danger to workers," Nanda said during a press briefing Thursday.