The new economics of downtown real estate and the reality of inflation's effects on lower-income workers collided Monday, with more than 4,000 janitors who clean Twin Cities office buildings walking off the job on Monday.

The janitorial workers, waving signs and chanting "We are the union" and "Shut it down," picketed throughout the day Monday in front of several downtown Minneapolis buildings, including Ameriprise Financial, IDS Center, Hennepin County Government Center and the Minneapolis Public Service Building. Lengthy negotiations between their employers and their union, SEIU Local 26, over the weekend failed to resolve differences.

Unless there's a down-to-the-wire agreement, about 1,000 nursing home workers will strike Tuesday. A group of Minneapolis-St. Paul International Airport workers will follow on Wednesday. About 400 Minneapolis Public Works employees also have authorized a strike. St. Paul teachers could strike next week.

"All those groups set a deadline back in October to take action in March," said Greg Nammacher, president of SEIU Local 26. "What is different here is that we are trying to coordinate and bring things to a head at the same time, because we do believe we are more when we are together."

Some of the groups, including janitors who work for retail stores, security guards and airport service workers, reached agreements with their employers last week.

But the workers who clean many of the biggest office buildings in the Twin Cities did not. They work for dozens of employers including ABM Industries, Marsden Services and Harvard Services. The employers say the union is seeking too much, especially during a sensitive time when the office real estate market is struggling amid lingering effects from the pandemic and the rise of remote work.

Abel Mendiola, who has worked cleaning buildings for 17 years, started walking the picket line at 7 a.m. Monday. He earns $15.54 an hour, he said.

"It's hard to pay the rent and bills," he said. "Food and electricity are very high."

Janitors were essential employees who worked through the pandemic, with many getting sick, incurring medical bills and receiving no pay while recovering, Nammacher said. Workers were doubly hit when inflation shot through the roof.

Monday's disruption prompted some downtown employers to postpone meetings and to alert their own employees that it was OK to work remotely.

The strike also won the support of the North Central States Regional Council of Carpenters and other building trades and Teamsters truckers who turned their rigs around Monday morning in order not to cross janitor picket lines downtown, Nammacher said.

Other workers joined the janitors in picketing Monday, including members of the nonunion group CTUL (Centro de Trabajadores Unidos En La Lucha) and FirstService Residential condo maintenance workers who are seeking to unionize.

Hundreds of strikers and supporters appeared at a Minneapolis City Council listening session Monday afternoon, with dozens testifying in favor of a proposed ordinance that, if passed, would create a Labor Standards Board.

If created, such a board would set citywide labor policies that address grievances particular to specific industries, said SEIU Local 26 lead organizer Dan Mendez Moore.

"We are here because we have children and families," office janitor Gladys Morales told council members and city aides. "We have several jobs and it's very difficult [to make a living]. We hope this ordinance passes so there is justice for all of us workers."

The SEIU originally called for 8,000 janitors and airport service workers like Morales to begin striking Monday. But that number slid to just over 4,000 after the SEIU reached tentative agreements with half of their employers.

On Tuesday, the workers at a dozen nursing homes — represented by SEIU Healthcare Minnesota and Iowa and UFCW Local 663 — will picket at six of the homes including St. Louis Park Estates in Roseville, St. Therese in New Hope, Bryn Mawr in Minneapolis and Cerenity in St. Paul.

The office janitors and nursing home workers will hold a joint rally at 1:45 p.m. on the steps of the State Capitol.