Last week, President Bush reaffirmed his support for overhauling America's immigration system to provide a path to eventual citizenship for the estimated 12 million illegal aliens in the country. One of the most contentious issues in the immigration debate is the effect that undocumented workers have on the U.S. labor market. VOA's Michael Bowman reports from Washington, where a panel of federal officials and academic scholars addressed the subject at a recent congressional hearing.

It is a basic economic principle: the more you have of something, the less it costs. So it would seem to stand to reason that the more workers you have in any particular industry, the less employers will have to pay in wages.

Republican Congressman Steve King of Iowa says illegal immigration is currently proving the validity of that theory, contending that a flood of low-skilled undocumented workers is depressing wages and causing greater unemployment for U.S. citizens who lack a university education.

"The reality is employers hire desperate aliens who will work for much less than Americans, driving wages down and making it impossible for American workers to compete," said Steve King. "And what about the claims that there are jobs that Americans will not do? That claim is a slap in the face to the millions of U.S. citizens who go to work every day, working those very same jobs side by side. [For example], 79 percent of all service [industry] workers are native-born."

Representative King, who opposes President Bush's immigration reform plan, sits on the U.S. House Judiciary Subcommittee on Immigration and Citizenship. He says those who favor granting eventual legal status to millions of undocumented workers are putting the interests of foreigners ahead of those of U.S. citizens.

"The American dream means that you are the driver of your own destiny, and you can work hard to be successful," he said. "But you cannot work hard towards that dream if your job is taken by someone willing to work for lower wages, or if wages in an entire occupation are depressed by illegal immigration."

But do economic data support the congressman's assertion? Not according to the Assistant Secretary for Policy at the U.S. Labor Department, Leon Sequeira.

"Over the past 10 years, foreign-born workers increased from 10.8 percent of the civilian labor force to 15.3 percent," said Leon Sequeira. "Yet during this time the national unemployment rate has declined. It was 5.3 percent 10 years ago, and it has declined significantly to 4.6 percent last year, and most recently - last month - 4.6 percent."

In addition, Sequeira says, wages of non-supervisory workers have risen, on average, nearly nine-percent above the rate of inflation.

But Sequeira was providing macro-economic numbers for the nation as a whole. What of specific industries where undocumented workers comprise a large component of the labor force, such as fruit and vegetable harvesting, hotel and restaurant work, and construction? The picture there is more complicated and nuanced, according to Brown University economist Rachel Friedberg.

"For example, if the supply of lettuce pickers in the Untied States increases through immigration, [economic] theory predicts that the wages of lettuce pickers will fall, and so will the wages of [other] workers with similar skills," said Rachel Friedberg. "But there will be an increase in the earnings of truck drivers, restaurant workers, supermarket stockers, and all the people who work with lettuce pickers in getting lettuce to our dinner tables."

In other words, a sudden infusion of new workers can depress wages in any particular segment of an industry. But the savings in production costs will benefit workers in other segments of that same industry, bringing gains that balance out or even surpass the wage loses suffered by the negatively-impacted group.

And there is another factor to consider, according to Friedberg: newcomers to the United States do more than earn a wage.

"Because immigrants not only work, but also spend money, the increased demand for goods and services will create jobs and raise wages throughout the economy," she said.

The consensus view among those who testified before the subcommittee is that immigration, whether legal or illegal, brings net economic benefits to the United States.

But costs do exist, and those costs are not shared equally. While there may be many winners, there will also be some losers as a result of immigration.

Several economists who spoke at the hearing suggested the best course of action is to continue to welcome newcomers, but to provide additional training and educational opportunities for those whose employment and earnings suffer as a result of the arrival of foreign-born workers.