SANTA ANA, Calif. — For foreign professionals in the United States, the rising unemployment rate is especially daunting.

Laid-off foreign workers are scrambling for temporary visas and seeking advice from immigration attorneys about how long they can legally stay in the country while hunting for jobs.

Even some foreigners here on visas or work permits are switching employers, fearing that an unstable job during a recession could ultimately lead to a one-way ticket home or kill their chance of getting a green card.

Caron Traub, 38, of South Africa panicked after losing her job as a business development manager for an envelope manufacturer. With plans for an April wedding in Atlanta to her Canadian fiance, who has a green card, Traub worried that she could be forced to leave the country before then and be unable to get back in.

"It's very scary stuff," said Traub, who applied for a temporary visa to stay in the country legally and look for a job.

An undetermined number of foreign workers have been casualties of the recession, which pushed the nationwide jobless rate to 6.7 percent in November, a 15-year high. Economists predict the jobless rate will climb through much of 2009 and could surpass 8 percent.

Foreign residents with valid visas that authorize them to work in the United States can qualify for jobless benefits if they meet the requirements of the state in which they file, according to the Labor Department.

Nearly half a million foreign professionals are working in the country on visas, known as H-1Bs, or have applied for green cards with support from their employers, said Stuart Anderson, executive director of the National Foundation for American Policy, a policy research group in Arlington, Va. Many came to the United States to pursue graduate degrees and have lived and worked here for years.

Those who lose their jobs in the downturn may head home or move to countries that have more lenient immigration rules. That could drive much-needed innovation in technology and engineering overseas in the years ahead, Anderson said.

"What you may find is there are people who could be future entrepreneurs in the United States who end up starting these companies in other countries," he said.

Companies are required to notify the U.S. immigration agency when a visaholder stops working for them, but the government does not track how many skilled professionals leave their jobs because of layoffs, said Bill Wright, an agency spokesman. There are many reasons a foreign worker might leave a company in good economic times as well as bad — for example, to move to a better job, he said.

Immigration lawyers say they have received an increasing number of calls from foreign professionals who have been terminated — many in the financial services industry as investment banks slash payroll to stay afloat.

Cyrus Mehta, an immigration attorney in New York, said he was fielding a call a week from foreign workers who lost their jobs in the last year.

Carmita Alonso, a partner at corporate immigration law firm Fragomen, Del Rey, Bernsen & Loewy, said she's worked with at least 100 visaholders in the same predicament since late 2007. "This is definitely worse than we've seen in quite some time," Alonso said.

Following the dot-com bust in 2000, many high-tech workers were laid off and some foreign workers returned overseas. This time, immigration attorneys say the pain began primarily in the financial sector — though manufacturing and technology companies have also started eliminating jobs.

One of the biggest challenges for laid-off visaholders is the lack of a grace period to leave. Companies must provide a return ticket home for workers, who may try to switch to another visa, such as a six-month tourist visa, to buy time to pack their bags or look for another job.

Immigrants seeking green cards — which would let them remain in the country permanently — face different problems. If they are laid off, they can stay and look for a new job but must find one before the government reviews their paperwork, which could take months or years, depending how far along they are in the process. The bottom line: no employer, no green card.

The demand for visas tends to mirror the rise and fall of the U.S. economy — which has many attorneys guessing that cash-strapped companies will ask for fewer visas this spring.

"I think they're looking at every penny and this is a short-term cost they may want to avoid," said Tim Barker, partner at Fragomen in Los Angeles.

For the past six years, the demand for the visas has surpassed a 65,000 annual cap put in place by Congress, with 163,000 applications filed last year.