Opponents of Arizona's tough new crackdown on illegal immigration are planning a protest march in Phoenix on Saturday.

Organizers briefed reporters about the march on Tuesday. They say they predict upward of 50,000 marchers will come from around the country.

Opponents plan to demand that President Barack Obama order federal immigration authorities not to accept custody of illegal immigrants brought in under the Arizona law.

And they want the Obama administration to revoke agreements that allow local police departments to enforce federal immigration laws.

The march is being organized by labor unions and civil rights groups.

Supporters of Arizona's law also plan a protest on Saturday.