President Reagan's famous ''safety net'' of programs to shield the elderly and poor may be sorely frayed by the 1983 budget, which the White House now is fashioning.
At least four of the seven programs embraced by the net reportedly are due for trims. Some endured their first cuts in the 1982 budget.
To begin with, the most meaningful programs to the poor - medicaid, food stamps, and aid to families with dependent children (AFDC) - are not included in the safety net at all.
All three of these major and fast-growing welfare programs are expected to feel the cutting edge of the knife wielded by David A. Stockman's Office of Management and Budget (OMB) in 1983.
Assuming Congress goes along with the cuts, millions of low-income Americans will feel the pinch this year and next, even if the programs officially included in the safety net escape unscathed.
Of these programs, three bulk enormously large, receiving well over 90 percent of the money that goes to the seven ''net'' programs.
These three - Old Age and Survivors' Insurance (the main social security program), medicare, and veterans' pension and compensation benefits - are not specifically targeted to the poor.
Many elderly people indeed would be poor, if they did not get their monthly social security check and health benefits through medicare. But these programs also go indiscriminately to all elderly Americans, including the middle and upper income.
Medicare recipients may be obliged under the 1983 budget to pay more of their medical bills - specifically a share of hospital costs from the second to 60th day of hospitalization, now covered by the government.
Of the three safety-net programs cited above, medicare may be the only one to be changed in 1983, although the formula for computing veterans' compensation could be altered.
Four safety-net programs are designed to help the poor - supplementary security income (SSI) for the aged, blind, and disabled; Head Start preschool education; summer jobs for disadvantaged youths; and free school lunches and breakfasts.
Altogether these programs get less than 10 percent of the money Congress appropriates for the so-called safety net.
Mr. Reagan reportedly has intervened to save Head Start from the budget ax. But the remaining programs - SSI, summer jobs, and school lunches - may be cut back.
Administration officials are in some anguish over this. They shy from the image, or impression, that they are out to hurt poor people. They search to find the fine line between eliminating waste and abuse from welfare programs and, on the other hand, depriving disadvantaged people who depend on the government to survive.
Their task is not made easier by the fact that President Reagan gives a relatively blank check to the Pentagon to boost defense spending and that tax cuts so far enacted benefit the upper end of the income scale.
''Many of these (welfare) programs,'' says Treasury Secretary Donald T. Regan , ''began worthily 15 or 20 years ago. Then they grew, partly because the fiscal dividend of inflation gave the government more money to spend.
''We are trying - not to eliminate many of these programs - but to shrink them back to benefit those people who truly need aid.''
''Is there real distress?'' Asks Murray L. Weidenbaum, chairman of the President's Council of Economic Advisers. ''Of course there is. But after several decades of growth of government programs you do not have improvement, but deterioration. So we must try a different approach.''
The safety-net concept attracted a spotlight of attention, simply because the President labeled the seven programs as such and indicated they were a shield for the needy that would not be pierced.
Now growing budget deficits are forcing Mr. Stockman's pruning knife to cut away at the strands of the net.
Meanwhile, programs like food stamps and AFDC - much more meaningful to many poor people than the safety net - took it on the chin in the 1982 budget, with more cuts to come in 1983.