WASHINGTON - Despite days of huddling behind closed doors, the eight U.S. senators drafting an overhaul of federal immigration laws blew a self-imposed deadline for its completion Friday and packed up to leave Washington as Congress took a two-week spring recess.

Several disputes appeared to be to blame for the setback in the bipartisan talks.

They include whether to cap the number of visas given to low-skilled immigrant workers at about 200,000 each year, how much those so-called guest workers should be paid and whether companies and businesses must advertise to hire American workers first.

Labor and business lobbies have clashed over guest workers in the past, and the two sides appeared stalemated again Friday after days of intense infighting behind heavy mahogany doors on a marble hallway off the Senate chamber.

"We take two steps forward, then we take a step back," said Sen. John McCain, R-Ariz., a group member.

Sen. Patrick J. Leahy, D-Vt., chairman of the Senate Judiciary Committee, said the two-week delay means the committee probably won't complete the bill by the end of April for consideration by the full Senate, as he had hoped.

McCain and Sen. Jeff Flake, another Arizona Republican, will take Sens. Charles E. Schumer, D-N.Y., and Michael Bennet, D-Colo., to visit the Mexican border next week. The draft bill would require more fencing, guards or other provisions for border security before illegal immigrants are allowed to apply for residency.

One rough patch this week was a disagreement over how much immigrants should be paid under a proposed new visa category for entry-level jobs such as dishwashers, housekeepers and janitors. Negotiators for the AFL-CIO and the U.S. Chamber of Commerce brought the Senate group a proposal for how the program might work.

Their plan would create a new bureau, funded by visa fees, at U.S. Citizenship and Immigration Services. The office would compare unemployment data and job demand to determine how many work visas to issue each year, up to a cap of about 200,000.

Workers granted the special visas would be allowed to change jobs after arriving, and would not be barred from applying for legal status as a permanent resident. The number of visas would rise or fall based on a formula, without a vote by Congress.

But the two sides couldn't agree if foreign workers should be paid the same wages as Americans.

The chamber argued that foreign workers should be subject to federal minimum wage law and that they should not be paid more than Americans. The AFL-CIO wanted the minimum wage for different job categories to be indexed off the median wage, saying that would produce more competitive wages for American workers.

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