Target Corp. reversed a long-standing policy Tuesday by agreeing to include new contract language that will strongly encourage its cleaning contractors to negotiate with the janitors who clean the big retailer’s metro stores.

The change is seen as a significant victory for the 150 nonunion janitors in the Twin Cities who have complained for four years that they were fired or harassed by their employers for trying to secure better pay and working conditions.

In one case last year, several janitors won a lawsuit against one Target cleaning vendor who refused to pay overtime despite forcing its workers to miss meals or work extra shifts.

Target thought it was “important to reiterate our strong commitment to maintaining high standards and complying with employment laws to our vendors,” Target spokeswoman Molly Snyder said in an e-mail. “Target is in the process of working to include new terms that support those priorities in our housekeeping vendor contracts.”

While seemingly modest, Target’s policy change “is a big deal because it opens the door and makes these companies have to sit down with their workers,” said Brian Payne, an official with the community group Centro de Trabajadores Unidos en Lucha (CTUL), which has championed the interest of janitors cleaning Twin Cities Target stores.

CTUL officials and janitors met privately with Target officials for more than a year in sessions that apparently have paid off.

“It’s the first time in history for retail janitorial workers,’’ Payne said. “The hope is that the Target policy will be implemented by these other stores.”

That could affect 1,000 Twin Cities janitors now cleaning Sears, J.C. Penney, Kohls, Michael’s and other stores, Payne said.

The store janitors, who are not represented by a union, make about $8 an hour. They work for cleaning contractors such as Carlson Building Maintenance in White Bear Lake, Diversified Maintenance in Florida, Prestige Maintenance in Texas and Eurest Services in Edina. None of the vendor companies returned phone calls seeking comment Tuesday.

In the past, Target repeatedly declined to comment publicly about janitors’ concerns, which include complaints about strict work rules that keep their pay low.

The janitors also noted that the separate class of janitors who clean Target’s corporate headquarters building in Minneapolis are unionized through the Service Employees International Union and make more than $14 an hour.

However, CTUL officials credited Target with intervening in past cases to improve work conditions.

In some cases, Target made phone calls to get fired workers reinstated, Payne said, and in other cases it reviewed workplace memos and interviewed janitors to learn more about work rules and conditions.

In a letter dated June 6, Jodee Koziak, Target’s chief human resource officer, wrote that Target appreciated its meetings with the CTUL and said those talks “will result in meaningful additions to Target’s vendor agreements. … As Target enters into new service agreements with Twin Cities housekeeping service providers over the next few months, the company will include additional language in those contracts aimed at promoting positive and productive dialogue between Target vendors and their workers.”

“I applaud Target’s decision to lead the retail industry in responsible subcontracting practices.” U.S. Rep. Keith Ellison said in a statement.

Minneapolis Mayor Betsy Hodges said: “Congratulations to the workers who remind us all that when we boldly come together … we can move mountains. I also want to extend my congratulations to Target for demonstrating that good corporate citizenship means engaging with the community and valuing its workers.’’