Janitors who clean big-box stores in the Twin Cities will head to the bargaining table as members of a union, labor leaders said Thursday, after enough retailers pressured their cleaning companies to allow it.

More than 500 mostly minimum-wage retail janitors announced they have joined the Service Employees International Union (SEIU) Local 26 and will start negotiating a contract next month, making the Twin Cities the first major metropolitan area in the U.S. where retail janitors are unionized.

"We were told that the industry was impossible to organize — this was a fractured, subcontracted industry," Veronica Mendez Moore, co-president of the workers' center Centro de Trabajadores Unidos en Lucha (CTUL), said at a news conference. "Despite these enormous obstacles, CTUL and retail janitors organized, stood up, fought and won."

While janitors in office buildings have been part of the SEIU for years and earn around $15 per hour and have health benefits, the people who clean retail stores have not been members of the union and are paid minimum wage or slightly more, and few have health benefits.

With the help of CTUL and SEIU, though, the workers — most of them Latino immigrants — have gradually worked toward Thursday's announcement, which janitors and their labor allies consider a watershed moment. Adding 500 janitors would swell the ranks of SEIU Local 26 by about 12 percent.

A key player in all this was Target Corp., which in 2014 was the first retailer to agree to a responsible contractor policy with retail janitors. As part of the policy, the cleaning contractors who employ the janitors were strongly encouraged to negotiate with the workers, and the workers agreed that they would not unionize until 60 percent of big-box stores in the Twin Cities area were cleaned by companies that allow their workers to unionize.

"When Target took that leadership step, the rest of the industry followed," Mendez Moore said.

Only in the past two weeks was the 60 percent threshold met, when Lund's & Byerly's and Whole Foods joined Target, Best Buy and Macy's in hiring cleaning companies that allow workers to unionize.

Via e-mail, Target spokeswoman Molly Snyder said, "We have also actively encouraged CTUL and our housekeeping vendors to have an honest and open dialogue that is focused on finding mutually agreeable solutions. We are very pleased by the progress that our vendors have made in that effort."

She added that Target did not specifically direct its contractors nor the CTUL what to do. "Instead, we continue to encourage and support both parties working together in good faith to address any concerns that are within their power to resolve," Snyder said.

A spokesman for Best Buy struck a similar tone in a statement.

"We appreciate what these third-party employees do to keep our stores clean," the spokesman, Jeff Shelman, said via e-mail. "We obviously do business with many companies, so we do not believe it is our place to be drawn into negotiations between a vendor or a supplier and their employees."

The four cleaning companies under which the workers will unionize are Carlson Building Maintenance, based in White Bear Lake; IFS, a division of Ohio-based Kellermeyer Bergensons Services; Leone's Building Service, based in Anoka; and Prestige Maintenance, based in Plano, Texas.

None of the companies responded to requests for comment Thursday.

CTUL and SEIU have been working toward this for six years. Workers first organized under the group, which works closely with the SEIU, in the fall of 2009. In subsequent years, they conducted short strikes six times. They protested in front of Target headquarters before the company agreed to the contractor policy. And they later picketed outside Home Depot and Macy's.

Through two federal class-action lawsuits, retail janitors recovered $1.1 million in unpaid wages and damages.

Maricela Flores, 43, has been a janitor for six years, three of them for Carlson Building Maintenance. She cleans a Target store in Shakopee, where she lives, and earns $9.50 per hour.

"I really hope to advance our wage that we're earning, but two benefits that are important to me are health insurance and paid sick days," said Flores, an immigrant from Mexico, through an interpreter. "What I really want to do is bring good food to the table for my kids, and put them in good after-school programs."

The next step for the workers is to negotiate a contract with their employers. Whether that will be the same contract other SEIU janitors work under will be decided at the bargaining table.

"That is to be negotiated," Javier Morillo, president of SEIU Local 26, said. "That's what we want."

Pascual Tapia, 43, has worked as a janitor for 10 years, and cleans the downtown Target store, while also traveling to other stores to fill in.

He said that negotiating for holiday pay, paid vacation and paid sick days will be important to him as a union member.

"We're hoping for a better wage, because we feel like we deserve it," Tapia said. "I make $12 an hour right now, but I hope to make $15."

Staff writer Kavita Kumar contributed to this report.

Adam Belz • 612-673-4405