The May First Coalition is holding a downtown march today that organizers estimate may attract thousands of people, including some from out of state.
The annual event typically focuses on immigrant and worker rights. This year it is expected to be a forum for protest against Arizona's new immigration law.
"Our call has to be very clear that we have to begin a real dialogue" on immigration, said Isabel Garcia, Pima County legal defender and an organizer with Coalición de Derechos Humanos.
The march is scheduled to begin at 10 a.m. at the El Casino Ballroom, 437 E. 26th St., and end with an 11 a.m. rally at Armory Park, 220 S. 5th Ave.
Supporters of the new law also plan to rally downtown this morning.
People from the group Arizonans for Immigration Control plan to set up across the street from the park in favor of the new law and Gov. Jan Brewer's position. Their rally is scheduled to begin at 10:30 a.m. on the sidewalk outside the Tucson Children's Museum, 200 S. Sixth Ave.
Similar rallies are planned in cities across the country, including Phoenix, Chicago and Washington, D.C.
Such rallies are typically set on May 1 because it's International Workers' Day and a traditional day of protest.