A union representing 4,000 janitors who clean Twin Cities commercial buildings, including skyscrapers in downtown Minneapolis and St. Paul, announced Thursday that they plan to strike next week.

Service Employees International Union (SEIU) Local 26 represents commercial janitors who have been in contract negotiations for the past four months, pushing for higher wages, paid sick days and a program to expand use of nontoxic cleaning chemicals, among other proposals. Union members voted Feb. 8 to authorize a strike and are planning a daylong walkout next week.

Iris Altamirano, Local 26 president, said 11 bargaining sessions “have gotten nowhere.”

“We had been working really, really hard to land this and it was our preference to not have to strike,” she said. “Our workers are very clear about why they’re doing it and who they’re doing it for, and that’s for their families.”

Local 26 is negotiating with 18 companies, most of which are part of the Minneapolis-St. Paul Contract Cleaners Association. The local represents commercial janitors throughout the seven-county metro, including those who clean the IDS Center, the Capella Tower — which houses the Star Tribune offices — the Ecolab building, and the Wells Fargo and U.S. Bank buildings in both Minneapolis and St. Paul.

John Nesse, an attorney representing the Cleaners Association in contract negotiations, said each employer has a contingency plan to make sure buildings are cleaned during the strike.

“We’re disappointed that the union has chosen to break off negotiations and call a strike,” he said. “We are looking forward to getting back to the negotiating table.”

Negotiations are scheduled to resume Feb. 28, Nesse said.

George Mullins, who’s been a janitor for 30 years and works for Marsden Building Maintenance cleaning Target headquarters in downtown Minneapolis, said his hourly wage of about $16 isn’t keeping up with the cost of living. Some of his co-workers work two full-time jobs to make ends meet, he said.

“We watch the news and they boast how good the economy is doing, but yet still they don’t want to economically support us,” Mullins said. “What happened to that trickle-down effect? It’s not happening.”

Elia Starkweather, who works for Harvard Maintenance, has cleaned Ameriprise Financial headquarters in downtown Minneapolis for nine years. She said she wants all employers to start providing nontoxic cleaning chemicals — the ones she used while working for a previous employer were so strong that sometimes her nose bled, she said.

Mullins and Starkweather, who is vice president with Local 26, are both on the negotiating committee. Both went on a one-day strike during the last contract negotiations in 2016.

Four years ago, Starkweather said, she was afraid to strike.

“There is a lot of fear in my blood, in myself,” she recalled, noting that in her native Mexico, strikes can result in violent clashes with police.

“I’m not afraid like before,” she said Thursday. “I’m very sure that we are going to get something from this.”

Correction: Previous versions of this story misstated when Elia Starkweather used strong cleaning chemicals that caused her nose to bleed.