WASHINGTON (AP) _ A House Republican who helped negotiate the Gramm-Rudman budget law proposed Thursday to ease its deficit limits but make it tougher for Congress and the president to skirt their responsibilities.

''Those supporters of Gramm-Rudman ... who refuse to consider changing its statutory deficit targets run the risk of loving it to death,'' said Rep. Willis D. Gradison Jr. of Ohio. Congress can't reach the the fiscal 1988 target of $108 billion ''even if we empty our arsenal of blue smoke and mirrors,'' he said.

''We not only can't hit the target, we can't even give the appearance of hitting it,'' said Gradison, a member of the House Budget Committee who was on the House-Senate conference committee that drafted the final Gramm-Rudman language.

The Congressional Budget Office estimates the deficit next year would be $169 billion unless cuts are made or revenues raised, meaning that lawmakers need a budget with $61 billion in savings.

In a ''Dear Colleague'' letter circulated to other House members, Gradison proposed raising the fiscal 1988 deficit target to $149 billion. Then, as in current law, the target would be cut by $36 billion a year until a balanced budget is attained.

When Gramm-Rudman was passed in 1985, the fiscal 1986 deficit was predicted at $172 billion and that was the basis for Gramm-Rudman's current targets. But the deficit ballooned to $221 billion, and Gradison said the targets should be adjusted to reflect it.

At the same time, he said, Congress should restore the automatic spending cuts that were a feature of the original Gramm-Rudman law but thrown out by the Supreme Court. Those cuts, which slash across-the-board if the targets are missed, would not only discipline Congress but force President Reagan to work more closely with Congress, he said.

Currently, the across-the-board cuts are imposed only if Congress passes and the president signs legislation to that effect, leaving considerable room for averting the issue.

Democrats in the House and Senate have been discussing possible changes in the deficit targets. But most have been hesitant to restore the across-the- board cuts because the only legal mechanisms would probably give more power to Reagan.

Sens. Phil Gramm, R-Texas, Warren Rudman, R-N.H., and Ernest F. Hollings, D-S.C., the original sponsors of the budget-balancing law, have proposed restoring the automatic spending cuts but without changing the targets.

The Senate was in recess Thursday but Larry Neal, spokesman for Gramm, said, ''Certainly at this point Senator Gramm would not be inclined to embrace any notion to ease the targets.''

Growth in the economy would add $70 billion in revenues to federal coffers next year, he said, so Congress should be able to meet the targets without a tax increase.

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