Hispanic groups are urging people to take part in a "Day Without Immigrants" on Monday by staying home from work and school and avoiding shopping trips, in an effort to press officials to legalise the status of the 12 million illegal immigrants living in the United States.
"We have to make our presence felt through our absence," organisers from the nation's most influential Hispanic groups said at their final press conference before the mass boycott.
But while the demonstration was planned by a network of organisations representing the largest US minority group, some 40 million Hispanics, the coalition called for solidarity among all US immigrant communities, encouraging them to show a united front in boycotting work and commercial transactions for a day so their full economic weight could be felt.
"We've unequivocally called on all families to participate in the Great American Boycott and the marches -- and that translates into not going to work, not going to school, not shopping and not selling," Nativo Lopez, president of the Mexican-American Political Association, said at Friday's press conference.
However, city and school officials and the "We Are America" coalition -- which includes the Roman Catholic Church -- are encouraging people to go to school and work and join the demonstrations later in the day.
Political leaders have also been divided over how the protests should be carried out.
US President George W Bush criticised the boycott as well as moves to create a Spanish version of the US national anthem.
He urged immigrants instead to learn English so they can sing the original version of the song.
California's Republican Governor Arnold Schwarzenegger also denounced the boycott, but the state's Democrat-dominated Senate approved a resolution supporting it.
Meanwhile, food giants such as Tyson Food Inc. and Cargill Foods announced the closing of at least eight plants, while Goya Foods announced a complete halt in its daily distribution.
All three companies said they understood the sentiments behind the protest.
"It's no surprise that food companies are taking a position favoring workers, given that many of them employ immigrants, most of them Hispanic and many of them illegal," Angel Luevano, spokesman for the League of United Latin American Citizens, said.
Wal-Mart, which employs more than 1.3 million people, has not yet announced what it will do if a sizable number of its Hispanic employees take the day off.
The US Hispanic Chamber of Commerce, however, cautioned that workers must first get their bosses' consent to be absent from work on in order to protect themselves from being fired. Nonetheless, it voiced support for the "just reform" the immigrants are seeking.
The stand taken by the chamber -- representing nearly two million Hispanic-owned businesses that bring in US$300 billion in sales each year -- was echoed by the National Council of Chain Restaurants, which represents 40 different chains with some 2.8 million workers.
Leaders from unions such as the AFL-CIO -- which represents more than nine million workers -- said they support the strike and pledged to join the demonstration.
But the United Farm Workers' Union, although it supports immigration reform, urged members to participate in the rally after work, to avoid being fired.
Meanwhile, a group of lawyers in Los Angeles announced that they would be outside the city's immigration office on May 5 to volunteer their services to anyone who is penalized for taking part in the demonstration.
"In California, the world's fifth-largest economy, one in every four residents was born elsewhere, so it is important to realize that our economy has come to depend on immigrants," Gloria Romero, the Democratic state senator who introduced the resolution supporting the boycott, said.
Though the economic impact of the "Day Without Immigrants" is hard to predict, some analysts expect a major social impact akin to the dawning of the US civil rights movement in the 1960s.