When Salvadoran Nelson Montoya learned that U.S. officials might not renew the temporary permit that has allowed him to live here for more than 15 years, he was ready to begin life as an illegal immigrant.

The 40-year-old cook said he wasn't prepared to give up everything he has built for himself and his family since escaping El Salvador's civil war and blighted economy in 1989.

"If they sent me away, I would have to come back," said Montoya, who is in the process of buying a house and has four children ranging in age from 11 to 20.

Montoya won permanent residency through another program late last week, but immigrant advocates say thousands of others will stay illegally if federal officials don't renew their temporary protected status this year. More than 300,000 immigrants, most from Central America, are in the U.S. under temporary protected status granted to those who fled dangerous conditions.

If their status isn't renewed, immigrant advocates say, parents and their American-born children could be separated, the number of illegal workers in the U.S. could skyrocket, and thousands of people could be forced back to countries that offer little.

"Now is not the time, because all the considerations have not been made," said Jose Lagos, president of the Miami-based advocacy group Unidad Hondurena. "The impact would be catastrophic."

Large numbers of Central Americans have settled in Dallas, Houston, Los Angeles, San Francisco, Washington D.C., Miami, Boston, Chicago and New York. Thousands of Hondurans and Nicaraguans came after Hurricane Mitch struck in 1998. A wave of Salvadorans followed in 2001 after a devastating earthquake.

But their temporary status must be renewed regularly, and it doesn't lead to the green cards that provide permanent resident status.

The status next expires Sept. 9 for 220,000 registered Salvadorans. It expires July 5 for some 70,000 Hondurans and 3,600 Nicaraguans. Homeland Security officials must make a renewal decision 60 days before the status expires, said Dan Kane, a spokesman for U.S. Citizenship and Immigration Services.

In the meantime, immigrant advocates and Central American government officials are lobbying for an extension, said Lagos. His group has started a petition drive to protect "hardworking, taxpaying, law-abiding immigrants."

"They're not terrorists," Lagos said.

In fact, says Dallas immigration attorney Jaime Barron, the program has helped the U.S. by creating a pool of workers and business owners who pay taxes and exert a large buying power.

"For them, having a work permit raises them from being in the poverty level to middle class, and some even beyond that," Barron said.

Advocates say stopping the program without offering another option would result in even more illegal workers -- a problem already so great that lawmakers and President Bush have proposed a guest worker program to reduce illegal immigration.

"First, they would lose their jobs, becoming a clandestine labor force," said America Calderon, a program manager at the Central American Resource Center in Washington D.C.

Many would have to be forced out and would try to return, creating an even heavier workload for immigration and border patrol agents, advocates and immigrants say. Because so many Central Americans support relatives back home, they could be less likely to depart voluntarily.

"I haven't slept since I heard the news," said Lidia Urbina, a 49-year-old who cleans apartments and takes care of the elderly in Miami to support her seven children in Nicaragua. "The situation of our country is critical. If people survive, it's because of us here."

Immigrant advocates point out that conditions in Central America haven't improved since the war and natural disasters years ago. Hurricane Stan last year destroyed infrastructure, the economies are still suffering, and violent gangs known as maras are a growing concern.

"If there is a deportation of all Nicaraguans, Salvadorans and Hondurans, imagine that situation that will occur in those countries," Calderon said. "Because they aren't ready for this wave of people."