Office janitors picketed at buildings across the Twin Cities metro Monday morning as they kicked off a three-day strike, after SEIU Local 26 and cleaning companies failed to reach a contract agreement over the weekend.

The picketing will start what the Service Employees International Union, or SEIU, is calling a "week of action," which will include rallies at Minneapolis-St. Paul International Airport and the state Capitol, plus other events meant to draw attention to the bargaining divide for those janitors, as well as nursing home workers and teachers planning strikes of their own.

SEIU said contracts have expired for more than 5,000 office and airport janitors and workers at more than 100 buildings. No tentative master-contract agreement was reached by a Saturday deadline with ABM Industries, Marsden Services, Harvard Services and dozens of other cleaning subcontractors.

The union also is planning a 5 p.m. rally Monday outside the Ameriprise Financial Center.

Last week, roughly 500 janitors who clean big-box retailers like Target, Best Buy and Cub Foods reached a last-minute deal, along with 2,000 security guards. Those agreements include increased pay and retirement benefits. For retail janitors, it would mean a bump in starting wages from $14.50 to $17 an hour over the life of the contract.

However, those contracts don't cover 4,000 SEIU members who clean downtown offices and at the airport and about another 1,000 people who provide other services at MSP. Bargaining has stretched for months, and SEIU said in a news release Sunday that a final session last Friday went late into the evening. The next meeting is scheduled for Friday.

Also on Monday, SEIU said workers and Minneapolis council members would speak out before a public hearing on a labor standards board that would study and recommend new workplace regulations to the council and Mayor Jacob Frey.

On Tuesday, employees at nursing homes represented by SEIU's health care chapter and Local 663 of the United Food and Commercial Workers expect to rally and picket at a St. Louis Park facility and later at the state Capitol as part of a one-day strike.

On Wednesday, janitors and airport workers will rally at the airport. On Friday, teachers with the St. Paul Federation of Educators and members of other unions have planned a march to the Capitol.

The teachers union in St. Paul authorized a strike date of March 11, although the school district hopes to pursue binding arbitration and reach a new two-year contract. In late February, Minneapolis public works employees also authorized a strike.

SEIU leaders said pay is one of the biggest issues for its members, arguing wages have not kept up with inflation. An attorney representing 10 commercial janitorial employers said last week that the union was making extraordinary demands and that wages already led the industry.