Tomorrow is International Workers Day. Chicago immigrants and their supporters are holding their third annual May Day march through the Loop. No one is expecting a turnout as big as in 2006 or 2007. But organizers say the march will show that the immigrant-rights movement remains strong. If it does, it’ll owe in no small part to a new level of union support.

Follow the May Day march route.

Laura Garza is a vice president of Service Employees International Union Local 1. She’s been busy mobilizing the union’s heavily immigrant membership for tomorrow’s march. This year, Garza says, the march takes on a different significance.

GARZA: This is a big election year. Over the years, we’ve told people, ‘Today we march, tomorrow we vote.’ Now we have to walk the walk.

Labor unions helped promote the march in previous years. But this year they’re also covering nearly all of its roughly $10,000 budget. The costs include stages and sound systems, T-shirts and toilets.

That support doesn’t go over well with retired electrician Mike Madia. He’s a union pensioner and a member of the Chicago Minuteman Project, which fights for tougher immigration enforcement.

MADIA: Using union funds to foster illegal immigration is wrong. Before they do anything about legalizing these people, the borders have to be completely sealed.

Madia says undocumented residents are overwhelming public schools, infrastructure and services. And even some immigrant advocates concede that workers without legal status can drag wages down.

THINDWA: That’s because employers are going to prefer a worker who’s more vulnerable, who’s without rights.

James Thindwa directs the Chicago chapter of Jobs With Justice, a group that builds community support for organized labor.

THINDWA: That worker can’t complain about working conditions. So the way to solve that is to create a path to legalization so that those workers have rights that protect them against abusive employers.

Thindwa will gather with other immigrant-rights supporters tomorrow at Chicago’s Union Park, where the march begins. But the organizers aren’t certain this year’s turnout will match the hundreds of thousands who showed up in previous years. Last year, a week before the event, immigration agents stormed a shopping mall in Little Village, a mostly Mexican neighborhood of Chicago.

CEPEDA: Guys with what looked like assault rifles — pointing them at women and children.

Former Chicago Sun-Times columnist Esther J. Cepeda says the raid galvanized many immigrants. But Cepeda doubts the May Day protests a few days later achieved anything.

CEPEDA: We had these marches across the country in all the big cities. But nothing came of them. And, in fact, four months later, in July, the immigration reform bill just failed.

The bill’s death extinguished hopes of providing a path to citizenship for the nation’s estimated 12 million undocumented immigrants. Extinguished, that is, until after this November’s election.

Immigration and Customs Enforcement, meanwhile, has steadily picked up the pace of deportations. The agency says it removed a record 280,000 immigrants last year. Carlos Arango of Casa Aztlán, a community center in Chicago’s Pilsen neighborhood, says that’s why he’s heading to Union Park tomorrow.

ARANGO: Undocumented workers should have the opportunity to regularize their immigration situation because immigration is no crime. People go from place to place, looking for better conditions of life.

Arango says marching is a right that immigrants must exercise.