Talk of immigration reform often centers on the fate of field hands and hotel maids, but the future facing engineers, computer programmers and statisticians also hangs in the balance.

With a shortage of American workers in some fields, highly skilled foreign workers are important to the U.S. economy, but immigration restrictions have hamstrung many companies who want to bring them in.

"The problems of the immigration system are not limited to the undocumented workers," said Laura Edgerton, head of the N.C. Immigration Lawyers Association. "This is also about advanced-degree professionals, people that could help our economy but are being shut out."

The Senate's proposed immigration bill, scheduled to be debated this week, would open the nation's door wider for skilled workers. Under the bill, the annual number of visas for workers with advanced degrees would grow from the current 65,000 to 115,000.

Business advocates favor the increase, but they say it is not enough to assure that all foreign workers who are in demand are able to get a visa. They add that the Senate bill will not ease the backlog of applications that plagues those who want to work in the United States permanently.

The visas for highly educated foreigners, known as H-1B visas, have become increasingly difficult to get. Businesses can begin applying on behalf of the workers they hope to hire in April of each year. In 2006, all the slots were taken by May. This year, the government received 130,000 petitions -- twice the number of available visas -- on the first day.

It used a random lottery to choose those who would get a visa.

Mike Plueddemann, director of human resources at DynPro, an information technology consulting company with an office in Durham, said that eight of the 29 visas he requested were denied. Those rejected were the most skilled, experienced candidates, he said.

"It's just pure, random luck," Plueddemann said.

Officials at several Triangle companies said they would rather fill the jobs with U.S. citizens and avoid the hassle of visas, which take hours of paperwork and cost more than $2,000 each. But they say that in a time of economic prosperity, when many high-tech industries are expanding and baby boomers are retiring, they can't find enough American workers. So they look to places such as India and China, which are producing engineers more quickly than the United States.

Immigration advocates said that when U.S. businesses cannot hire the foreign workers they need, they create jobs in other countries instead. DynPro, for example, has offices in India.

Ushma Mehta, 22, is a graduate student in computer engineering at N.C. State University. When she graduates in December, she will be one of those staking her hopes on the H-1B visa. She said she wants to work in the United States, but if she doesn't get the visa, she'll return to India and take one of the many high-tech jobs that are being sent there.

"I'd still be happy," said Mehta, who is completing a master's degree in only a year and a half. "But it's the loss of the U.S. government if they don't get good people to stay on, because we'll go back home."

But even if Mehta gets the visa, that doesn't assure her the permanent right to work in the U.S. The visa lasts three years and is often extended for another three. After that, foreign workers need "green cards," which indicate they have become lawful permanent residents.

Sanjay Lulla, a computer programmer and analyst at DynPro who is from India, said he will finally get a green card this year, after four years of waiting. During that time, he was unable to change jobs, because his visa is sponsored by his employer.

He said that the endless delays and restrictions are so frustrating that they have driven many of his friends back to India or to Canada, where the process is simpler.

(Staff writer Sabine Vollmer contributed to this report.)