NEW YORK (CNNMoney.com) - Americans don't want to dig dirt for $9.21 an hour.

At least that's what Tom, the president of a large nursery operation in the Ohio, believes. He says his business would never survive without the 350 seasonal employees that come from Mexico every year to move plants, load trucks and trim trees through the current H2A "guest worker" program, which grants temporary work visas.

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"The guys from Mexico are here to better their lives in Mexico, they are here to work hard and get the job done, their attendance is 99 to 100 percent," he said. If he had to hire local citizens, they would only "last a day to two days to a month."

And so Tom, like many other business owners across the country, is paying close attention to the current immigration debates in Congress. For his part, Tom says he wishes lawmakers would not only protect but streamline the nation's guest worker program so he can be assured a reliable supply of workers.

"If we had to hire these people locally we would never get up to speed," he told CNNMoney.com by telephone. (For obvious reasons, CNNMoney.com agreed not to use his last name).

No industry would be harder hit than agriculture if the supply of migrant labor is cut off, according to the American Farm Bureau.

"We would see up to a third of the fruit and vegetable sector go out of business almost right away... $5 to $9 billion dollars would basically be handed to our neighbors overseas," according to American Farm Bureau Labor Specialist Austin Perez.

But the AFL-CIO has spoken out against such guest worker programs, calling them "a bad idea."

"They cast workers into a perennial second-class status, and unfairly put their fates into their employers' hands, creating a situation ripe for exploitation," AFL-CIO President John Sweeney said in a statement.

There are currently 11.5 to 12 million unauthorized migrants living in the U.S., according to a study published by the Pew Hispanic Center, which accounted for about 5 percent of the labor force as of March 2005.

According to the study, those workers are mostly concentrated in blue-collar service occupations, including farming, cleaning, construction and food preparation.

A chef at a prominent restaurant chain in New York City said that restaurants routinely hire illegal immigrants to work long hours washing dishes. The only people doing the dishwasher job are people that are desperate to work, he said. "The job sucks; they've gotta be f***ing hungry."

Undocumented workers earn considerably less than working U.S. citizens, according to a study by the Urban Institute. About two-thirds of undocumented workers earn less than twice the minimum wage -- the point at which workers are classified by the institute as "low wage."

He said that if his restaurant was forced to pay their dishwashers more to lure American workers, then "it would increase your menu prices by a dollar a plate across the board."

And often, he acknowledges, the restaurant will turn the other cheek when it comes to checking their workers' legal status. "We won't talk to anyone without ID," he said -- even if it's a terrible forgery. "You have to have a piece of paper, but it's like, just show me something."

On the record, the National Restaurant Association has praised the Senate Judiciary Committee for approving legislation to revamp America's immigration system.

The Senate Thursday was debating the bill which would create a new guest worker program and give millions of illegal immigrants a chance to become citizens.

But George Borjas, a professor of economics and social policy at the John F. Kennedy School of Government, calls the bill "an economic disaster waiting to happen." By allowing an influx of labor into the general labor pool, the legislation would in effect increase labor supply and keep wages low, he argued.

"It makes workers poorer and employers richer" Borjas said, as if lawmakers were handing employers "a big check."

In addition some Senate Republicans support a comprehensive approach but do not like provisions that offer foreign temporary workers and illegal immigrants a chance for citizenship. They argue it would reward illegal behavior and put those people ahead of others who have been waiting years to enter the country legally.

The House Republicans passed a bill in December which not only omitted a guest-worker program and a legalization process, but also made it a felony to come across the border illegally or to help illegal immigrants. The House bill also authorized construction of 700 miles of security fencing along the U.S.-Mexico border.

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