WASHINGTON (AP) _ The reaction to a bipartisan immigration reform plan being outlined today is generally favorable -- from Latino advocacy groups, the U.S. Chamber of Commerce and organized labor. But some are also sounding a note of caution.

The head of the AFL-CIO is questioning a proposal that would require illegal immigrants to provide proof of employment before they can gain legal status. Richard Trumka says it could exclude millions of workers who can't provide proof, because they've been forced to work "off the clock" or they are independent contractors.

The plan includes a path to citizenship for illegal immigrants who are already in the United States. But Clarissa Martinez of the National Council of La Raza says the path must be one that is workable. She says it can't be "so rigorous that those seeking to apply would not be able to get there."

And the American Civil Liberties Union is taking issue with a proposal to require employers to use an electronic system to verify employment. The ACLU calls it a "thinly-disguised national ID requirement."

The deal being announced today also covers border security and "guest" workers.

The White House calls it a "positive" development.