A trio of bargaining units representing about 250 St. Paul public employees on Tuesday served the city with a lawsuit challenging its COVID-19 vaccine mandate — the third complaint in the past two weeks.

The union for a wide range of workers — from snowplow drivers to many of the manual laborers in the Public Works and Parks and Recreation departments — joined the police and fire unions seeking a regular testing option for employees unwilling to receive the shots.

In late October, Mayor Melvin Carter announced that the city's nearly 4,000 employees would be required to provide proof of vaccination by the end of the year. Unlike most of its peers, St. Paul will not offer a testing alternative, though Carter said the city will make exceptions for those who qualify for medical or religious exemptions.

The complaint — served on behalf of the International Union of Operating Engineers (IUOE) Local 49, Teamsters Local 120 and the Laborers' International Union of North America (LiUNA) Local 363 — said the city failed "to meet and negotiate in good faith with respect to a unilateral change to the terms and conditions of Tri-Council members' employment."

"The city of St. Paul's position here is extreme and unnecessary," Jason George, business manager for IUOE Local 49, said in a statement Tuesday. "A testing option is reasonable; it is responsible; it can be effective, and it should be offered."

The union filed a grievance last week alleging that the vaccine mandate violated its collective bargaining agreement, according to the complaint. Like St. Paul's police and fire unions, the group is arguing the city must negotiate an agreement or take the matter to a third-party arbitrator.

City spokesman Peter Leggett has said that unless the court orders otherwise, St. Paul will proceed with its mandate as planned, meaning employees who do not complete a vaccination series by Dec. 31 could face discipline or termination.

"Amid rising case counts and record level hospitalizations, protecting our city workers and our community from this global public health crisis is as vital as ever," Leggett said Tuesday.

Several members of the three bargaining units have requested exemptions, but none has heard whether they will be granted, the lawsuit said. The city had received 168 exemption requests as of Thursday.

"We're running up against a deadline here in a couple weeks, and we need answers," said Chris Wachtler, an attorney representing the coalition of the IUOE, Teamsters and LiUNA, as well as the firefighters union.

Wachtler said he planned to file the suit in Ramsey County District Court late Tuesday.

The court has scheduled a virtual hearing in the St. Paul Police Federation case Thursday afternoon, when the union will ask a judge to grant a temporary restraining order that would protect members from losing their jobs for refusing to be vaccinated while litigation continues.

"I want to be clear that we are not anti-vaccine and do not want anything to do with that hyper-political and divisive debate," George said in a statement, adding that he has received the vaccine and encouraged members to do so. "However, we do not believe anyone should be fired for making a personal health choice not to get vaccinated."