The union representing St. Paul firefighters filed a lawsuit Thursday challenging Mayor Melvin Carter's mandate that city employees get a COVID-19 vaccine by the end of the year.

In an argument mirroring a complaint filed by the St. Paul Police Federation last week, the firefighters union is arguing that the city committed an unfair labor practice "by failing to meet and negotiate in good faith" the terms of the vaccine mandate.

In an announcement to the city's nearly 4,000 employees in late October, Carter said St. Paul would not offer a testing alternative for workers who choose not to get shots — unlike most other local governments in Minnesota.

"COVID remains the leading cause of death for firefighters in our country," Carter said in a statement Thursday. "Amid the ongoing uncertainties of this pandemic, we'll continue doing everything we can to protect our city workers and our community from this global public health crisis."

The city has received 168 requests as of Thursday for medical or religious exemptions, which the Department of Human Resources is processing on a case-by-case basis, said Peter Leggett, Carter's director of communications.

"We are not opposed to the vaccine," said Mike Smith, president of the 430-member union. "The city right now is not providing my members with enough information to make their decision. The deadline is fast approaching, and we don't have any answers."

Smith said none of the roughly 80 firefighters who asked for exemptions have learned whether their requests will be granted.

"If you're doing a two-shot vaccine, you're going to have to start like a week from tomorrow. And we still don't have answers on exemptions," said Chris Wachtler, an attorney representing the firefighters union. "That is a huge frustration."

Leggett said the city is "working to process and complete" requests prior to the deadline.

"Unless or until the court orders otherwise, we will continue moving forward with our vaccine policy, which requires city workers to complete a vaccination series by December 31, 2021," Leggett said in an e-mail.

Employees who do not provide proof of vaccination will not be able to work and may be subject to discipline, he added.

Both the fire and police unions are asking a Ramsey County judge to issue a temporary restraining order to protect members from losing their jobs while litigation continues. The lawsuits argue that state labor law requires the city to negotiate an agreement for a vaccine policy or take the matter to an arbitrator.

The complaints cite an ongoing case in Chicago, where a judge ruled the city cannot enforce a deadline for police officers to get vaccinated unless the issue goes to arbitration.

A hearing on the police union's request for a temporary restraining order is scheduled for Thursday, and attorneys said the fire union lawsuit could be addressed at the same time.

Leaders of both unions have expressed concerns about staffing levels if employees lose their jobs for refusing to get vaccinated.

"That could result in mandatory overtime. We could be shutting down rigs," Smith said. "The city doesn't have an answer to that either."