“Nothing gringo,” warns the rallying cry of Mexican activists calling for a boycott of all U.S. businesses south of the border on May 1.

The campaign, aimed at pressuring Congress to legalize undocumented migrants, was timed to coincide with “The Great American Boycott,” in which activists are urging migrants in the United States to skip work and avoid spending money to demonstrate their importance to the U.S. economy.

The Mexican boycott was being promoted on Web sites and through e-mail messages, one of which warns that “people shouldn’t buy anything from the interminable list of American businesses in Mexico.”

“That means no Dunkin’ Donuts, no McDonald’s, Burger King, Starbucks, Sears, Krispy Kreme or Wal-Mart,” the message said.

Promoted by some of the same groups that organized massive immigrant marches across the United States, the protest – also dubbed “A Day Without Immigrants” – comes as Congress debates immigration bills proposing everything from toughened border security to the legalization of all 11 million undocumented migrants in America.

Mexican unions, political and community groups, newspaper columnists and even some Mexican government offices have joined the call for a parallel boycott of U.S. businesses in Mexico. For some it’s a way to express anti-U.S. sentiment, while others see it as part of a cross-border, Mexican-power lobby.

Advocates occasionally missed their mark in identifying boycott targets. For example, they incorrectly identified Sears stores in Mexico as American owned even though Mexican billionaire Carlos Slim bought Sears Mexico operation in 1997.

And in an ironic twist, the protest targets the U.S. business community – one of the strongest supporters of legalization or guest-worker programs.

“Boycotting would only hurt corporations that are backing what people want done in the immigration bill,” said Larry Rubin, chief executive officer of the American Chamber of Commerce in Mexico.

In place of a boycott, Rubin encouraged Mexicans who have relatives in the U.S. to urge family members to write to their lawmakers in support of comprehension immigration reform.

Some organizers of the U.S. rallies have told people not to risk their jobs or education after some workers and students were fired or cited for truancy. But many others say marchers want to make the sacrifice to show the importance of immigration reform.