Congressional Democrats seek to keep Salt II alive, slow SDI. Success seems unlikely, but political gains are expected if Reagan vetoes arms efforts

Congressional Democrats are moving to alter White House arms strategy on two fronts - attempting to force continued compliance with the SALT II accord and to slow development and testing of the Strategic Defense Initiative (SDI). The House of Representatives has voted to block funds for deploying weapons that exceed the limits set by the unratified 1979 SALT II treaty so long as the Soviets observe those limits.

House members also have agreed to ban the use of money for development, testing, or deployment of any antiballistic missile (ABM) system - including those developed as part of SDI.

Last week the Democratic-controlled Senate Foreign Relations Committee attached a nonbinding resolution to its State Department authorization measure that calls on the Reagan administration to adhere to the narrow interpretation of the 1972 ABM Treaty.

And the Senate Armed Services Committee added an amendment to its defense authorization bill limiting SDI development and testing to the narrow interpretation of the ABM Treaty, unless Congress passed a joint resolution lifting the restrictions.

The committee also voted $4.5 billion for SDI in fiscal 1988 - less than the Reagan administration's $5.7 billion request, but more than the $3.6 billion allocated by the House.

Waiting in the wings is a Senate proposal that would force US compliance with SALT II, similar to the measure the House passed last week.

The Senate's SALT II bill has attracted 49 co-sponors, including some Republicans.

The SALT II and ABM measures still face delaying tactics by Senate Republicans. They could be saddled with amendments designed to make final approval difficult.

The vehicles for these initiatives were amendments to the Defense Department authorization bill for fiscal 1988, which begins Oct. 1.

Meanwhile, the Senate has taken steps to force the Reagan administration to accept a traditional, narrow interpretation of the 1972 ABM Treaty. This would essentially block advanced deployment of a space-based SDI system.

If those efforts fail, and Congress sends legislation containing the arms control measures to the President for approval, a veto is almost certain.

Democratic strategists admit it would be nearly impossible to find the necessary two-thirds majority in both houses to override a presidential veto. But by then, they say, public awareness of Democratic frustration with the administration's arms-control record would have been raised.