Ninety national organizations with a combined membership of nearly 40 million declared war yesterday on President Reagan's proposed cuts in Social Security.

"It is wrong to wring tens of billions of dollars out of retiree benefits so that they may be applied to other parts of the federal budget," said United Auto Workers president Douglas Fraser, speaking for the Save Our Security (SOS) coalition at a press conference. "We oppose all the cuts," said former Social Security commissioner Robert Ball.

On Capitol Hill, meanwhile, House Majority Leader Jim Wright (D-Tex.) told reporters that action on the budget, reconciliation and tax measures has priority over any Social Security bill; therefore, it appeared highly unlikely that the House would take up a Social Security financing measure soon -- certainly not before the August recess.

"We've got a full plate," Wright said, adding that Social Security is not in imminent danger of collapse, so there is no need to put everything else aside for it. Some interpreted his remarks as signaling that Social Security might not even come up until next year.

In another development, the National Federation of Independent Business released a national survey that found that the public, by 2 to 1, would rather see taxes raised than Social Security benefits cut.

While SOS was announcing its all-out opposition, the House Select Committee on Aging, in conjunction with the Congressional Black Caucus and the National Caucus on the Black Aged, held a meeting in the Cannon House Office Building where one black spokesman after another denounced the Reagan administration for its planned cuts in Social Security and other social programs. "Being old, black and poor, there are three strikes against you," shouted Rep. Harold Ford (D-Tenn.) to applause.

The Reagan proposals to lower Social Security benefits for future retirees, sharply penalize those who retire at 62 and make it much harder to get disability benefits were blasted by SOS coalition leaders such as Fraser; Amercian Federation of State, County and Municipal Employes and AFL-CIO spokesman Jerry Wurf; National Council of Senior Citizens chief Bill Hutton, former Social Security commissioner William J. Driver and representatives of organizations such as the National Education Association. rOthers in the coalition include Hyman Bookbinder of the American Jewish Committee and the National Conference of Catholic Charities.

Ball said that the immediate financing shortfall of the trust funds could be met by borrowing from the Medicare trust fund and the Treasury, to be repaid with interest, and that Social Security then would be in good shape until the end of the century when the aged population will begin to increase. But he and Driver said the average worker will be supporting fewer children then, so he will be able to make larger Social Security contributions.