Washington — It's now or never for this session of Congress to decide whether to tighten immigration laws.
Declaring that US borders are ''porous'' and that the situation is ''out of control'' - with half a million or more illegal aliens entering annually - the chairmen of two congressional immigration subcommittees introduced a bill that for the first time would prohibit, by federal law, the hiring of illegal aliens. A spokesman for the US Chamber of commerce immediately called the proposed program ''unworkable.''
At a joint press conference, Sen. Alan K. Simpson (R) of Wyoming and Rep. Romano L. Mazzoli (D) of Kentucky, chairmen of respective immigration subcommittees, offered a comprehensive new compromise measure. The fate of immigration reform legislation in this Congress probably hangs onit.
Following earlier Reagan recommendations, the proposed new bill would also allow millions of illegal aliens who have been in the US since 1978 to become permanent residents. Estimates vary from 3 million to four times that number. The bill would also streamline the program of admitting temporary farm (''guest'') workers, without setting a limit.
Employers would have to verify that prospective employees are entitled to work, a provision which the US Chamber immediately declared too costly -- $3.5 billion to start, it asserted. Valid identification could be a passport, birth certificate, social security card, or special card issued by the Immigration and Naturalization Service, though the latter could be used for no other purpose.
Tighter restrictions have been recommended under the Ford, Carter, and Reagan administrations and half a dozen surveys have been made, all reporting that the situation is getting out of hand. The emotional issue has brought sharp divergence from many racial, cultural, and business groups.
''The major thrust of the bill is to make it illegal to hire illegal aliens, '' Mr. Mazzoli said, adding it would also strengthen the Immigration and Naturalization Service. ''Illegal aliens come here to work and unless we end that lure, the flow will never stop.''
Senator Simpson estimated that half a million illegals enter the US annually. Secretary of State Alexander M. Haig Jr. recently used the figure 1.5 million. At the present time, unemployment in the US is climDing toward 9 percent.
Hostile reaction by employer groups indicate the problems ahead for the proposal. The US Chamber of Commerce commented after the press conference, ''The legislation would concentrate national immigration policy on requiring identification checks of US citizens and on the penalties and collection of penalties from employers.''
Christopher Luis, a labor attorney for the chamber, added: ''A law that requires the federal government's permission before a US citizen can accept a job and before an employer can hire that US citizen is both extremely costly and unworkable. The government would be overwhelmed trying to regulate the dynamics of the job changing practices of our national work force.''
Anticipating employer hostility to the Simpson-Mazzoli measure, which the authors call the ''Core Bill,'' a series of steps is provided, amounting to a three year phase-in before it is fully effective. TheJustice Department would set up a procedure to identify and authorize aliens who want to work in the US. Civil liberties spokesmen charge that the proposal might require Americans to carry identity cards. The new bill, however, stipulates that any ID card required by the Justice Department could not be required for any purpose other than identifying an alien's eligibility for work.
A 16-member commission under the Rev. Theodore M. Hesburgh, named by President Reagan, made recommendations on immigration last year. It voted for some kind of sanctions on employers who hire illegals, but was divided sharply on how to do it.
In many respects the bill follows the Hesburgh recommendations, but takes a more specific line on sanctions. Penalties for hiring illegals are graduated: there would be no penalty the first six months. During the second six months, a warning and $1,000 fine or a $2,000 for the second offense. Penalties could rise to $5,000 and five years in jail.