AS GOP lawmakers try to impose the strictest limits on legal immigration in recent history, a bevy of business groups is lobbying to maintain access to a pool of talented, foreign-born labor. Detractors charge that legislation now moving through the House and soon to be proposed in the Senate is antibusiness, bad for the economy, and against the tenets of the Republican revolution. This week the House Judiciary Committee considered a bill, proposed by chairman Lamar Smith (R) of Texas, to cut legal immigration by almost 30 percent. The measure would prevent adult children and siblings from accompanying those admitted and require employers to verify new hires' legal status. Mr. Smith says his goal is to eliminate workers who undercut US wages, take American jobs, and settle into the welfare system. But his bill has angered high-tech employers worried that a more limited pool of skilled foreign workers will undermine hard-won competitiveness. Many business advocates are confident Smith will amend his bill to help redress their concerns. More troubling to Rick Swartz, an immigration expert and strategist for Microsoft, is what looms in the Senate. Sen. Alan Simpson (R) of Montana is taking an even tougher stand with a bill to cut legal ''skill-based'' immigration from its current level of 140,000 people per year to 75,000. The legislation would also make it more difficult for workers to get temporary visas, require foreigners to prove three years of experience overseas before working in the US, and impose a stiff fee on employers of immigrant labor. The lawmakers' efforts largely reflect recent recommendations from the US Commission on Immigration Reform, chaired by former Texas Congresswoman Barbara Jordan (D). But such proposals have business interests crying foul. ''What we've been doing for the past seven months [of Republican leadership on Capitol Hill] is weeding out big government,'' says Nelson Litterst, a National Federation of Independent Business lobbyist. ''But now we're inviting it back, trying to pile more regulations on business and impose higher taxes.'' ''The immigration issue is one that raises a lot of contradictory impulses,'' concedes John Bolton, president of the National Policy Forum, a GOP think tank. ''But what it boils down to is a matter of sovereignty....That's not a matter of regulation...but preserving our resources from being depleted by people all over who see the US as an economic and political magnet.'' While lawmakers are tapping into widespread resentment against immigrants, legal immigration's defenders are debunking what they say are myths. The Urban Institute in Washington, D.C., recently released a study that shows legal immigrants generate upward of $30 billion more in federal taxes than they cost the government. Less than 5 percent of legal immigrants are welfare-dependent, the Institute says. US companies, already scrounging for skilled American workers, cannot afford to lose the option of foreign hires, says Warren Leiden, executive director of the American Immigration Lawyers Association and an adviser to numerous high-tech firms. Mr. Leiden, who served on the Jordan commission and was its sole dissenter, says his clients demonstrate that American firms need the engineering, marketing, and management experience of foreigners - who often are educated in and familiar with the US. Over half of the graduates spilling out of US university research labs and technology programs are from Asian, European, and Latin American countries, says Leiden. ''They are familiar with cutting-edge technologies,'' Leiden says. Mr. Simpson's draft bill would prevent US companies from tapping that resource, he adds. Business executives from Microsoft to Motorola extol the benefits of a brain-gain. They point to Canada, Australia, and other high-tech societies which choose immigrants by occupational training. ''When Microsoft just rolled out Windows 95, the company needed to translate it into 31 languages and cultures,'' says Leiden. ''You can't just use someone who has taken a two-year foreign-language course and expect that person to do the production and marketing needed to make successful sales abroad.'' Frank Sharry, executive director of the National Immigration Forum, says it's dangerous to lump those who come to the US legitimately with illegal immigrants. ''Members of Congress are presuming that the illegal immigration is too difficult to solve, so they're trying to fool the American people into believing they're solving 'the problem' by slashing the levels of legal immigration,'' Mr. Sharry says. ''In a perverse way, this legislation will increase the incentives for illegal immigration.''