Sen. Jake Garn, R-Utah, is continuing to pressure President Bush not to veto a bill that would punish foreign companies or countries that help proliferate chemical arms.

This time, he persuaded 70 other senators - more than the two-thirds of the Senate needed to override a veto - to sign a letter warning Bush not to veto the Omnibus Export Amendments of 1990.In debate on the bill last week, Garn pleaded for Bush not to veto it despite opposition from the State Department - which complains the bill would generally not allow the president the option of waiving sanctions if he feels it is necessary.

The bill would mandate U.S. import restrictions for one year on foreign companies or countries that the administration determines are helping develop or build chemical or biological weapons.

The letter from the senators told Bush, "You have made eradication of chemical weapons a national priority and you urged the Congress to pass sanctions legislation. We have answered that call and believe a veto on these narrow grounds would be contrary to our shared commitment to eliminate chemical weapons."

The letter noted that in the case of an offending foreign company, the president could decide whether to impose sanctions based on what action its own government may have already taken.

In the case of an offending country, the president is allowed to choose the most appropriate sanction to fit the violation. For both companies and countries, the president can waive all sanctions after a year.

"This is broad discretionary authority," Garn said. "In my view, it is more discretionary than the Toshiba sanctions language I added to the trade bill in 1988, which also faced a veto threat."

That bill temporarily banned imports from some Toshiba subsidiaries in punishment for it helping the Soviets to develop submarine machinery so quiet it cannot be detected by sonar.

The senators said that a veto also would destroy other important parts of the bill, such as sanctions against Iraq and against those aiding in missile proliferation.

"The result is a very large and comprehensive bill addressing the declining threat in Eastern Europe and the rising challenge of proliferation and instability in the Middle East," Garn said.