How wide should US hold its door for immigrants?

Foreigners are pouring into the United States in greater numbers than at any time since the early 1900s. A million applications for admission are in US consular offices around the world.

The visit of Mexican President Jose Lopez Portillo to Washington June 8 and 9 may precipitate a showdown on the issue of immigration, and on Ronald Reagan's own position on it. The President has hinted that he favors a revival of the guest worker, or "bracero," program. Any administration effort to implement such a program, however, would almost certainly precipitate an emotional battle in Congress.

Here are elements in the situation:

* Demographers say the world population increase is ominous: Every 24 hours the equivalent of a new Des Moines (pop. 200,000) joins Earth's inhabitants, and every year, the population of a new West Germany (73 million).

* The US neighbor to the south, Mexico, has a growth rate of 3.3 percent compared with the US rate of 0.8 percent. The US Border Patrol acknowledges it is unable to halt illegal entry.

* Guards on 6,000 miles of US land border number only about 350 at work at any one time --about the same number as are traffic policemen in New York City.

* The Select Commission on Immigration and Refugee Policy under Theodore M. Hesburgh, in its final report March 1, said the situation is "out of control" and recommended penalties on employers who hire illegals and an identification card for workers. It estimated 3 million to 6 million illegals are in the United States. Other estimates have gone as high as 10 million. (Current US unemployment figures equal only about 8 million.)

President Reagan has referred the Hesburgh report to a task force under Attorney General William French Smith, with recommendations likely to be forthcoming before the Portillo visit.

Oil-rich Mexico has a population of 68 million, likely to explode to 134 million by the year 2000, and a quarter of the work force is believed either unemployed or underemployed. In 1978 Agency for International Development administrator John J. Gilligan declared that "one-quarter of the adult Mexican work force is in the US because they can't find work in their own country."

The US admits twice as many immigrants as the rest of the world put together. Recent Roper polls show the public overwhelming favors curbing immigration and ending illegal entries. Theoretically, legal migration is limited to 270,000 newcomers annually, but exemptions for families and for refugees are elastic and the actual number is around 800,000. Congress has admitted 450,000 Indochinese since 1975, and President Carter accepted some 125,000 Cubans and 12,000 Haitians last year in the the "boat lift."

During the campaign, Mr. Reagan indicated to a Hispanic audience in Texas that he would grant visas to undocumented aliens. In an interview with Walter Cronkite on March 3, after taking office, he said that admission of Mexicans is a "safety valve" for a friendly neighbor that would help preserve "stability south of the border."

Reports from the White House say the administration is considering a revived bracero program similar to the one that brought 4 million to 5 million Mexican farm workers into the country from 1942 to 1964.

Guest-worker programs have been tried and generally dropped in Germany, France, Switzerland, and the Netherlands. Extraordinary political road blocks in the US, led by high domestic unemployment, appear to stand in the way of a revival here. But it is hard for Americans, whose Statute of Liberty welcomes the "huddled masses," to close the "golden door."

The new Reagan austerity budget slashes funds for the US Naturalization Service which patrols the border. The patrol has been so short of funds that gas for its vehicles has been rationed.

"Hundreds of thousands of persons annually enter this country outside the law ," the final report of the Hesburgh commission said.