Seventy privately insured savings and loan institutions remained closed today under executive order as the state legislature considered an emergency plan that would reopen some by the end of the week and would force others to liquidate or merge.

But federal government sources said so many of the institutions are weak or otherwise ineligible for federal deposit insurance that it will be a long time before the state can resolve the crisis.

Depositors at the shuttered institutions cannot get to their funds until at least Wednesday, under terms of an executive order issued today by Gov. Richard F. Celeste. The 70 savings and loans were closed Friday to stop a run. The state's 217 savings and loans with federal insurance continued to do business and experienced no unusual withdrawals Friday or today.

The House, meeting in special session, approved the emergency plan, 85 to 2. A similar measure bogged down late tonight in the Senate, where the Republican majority said it had been unable to reach a consensus.

The plan, devised late Sunday by Celeste, would allow the 70 closed institutions to reopen as soon as they apply for federal insurance protection and are judged eligible by the state superintendent of savings and loans.

State officials said about 20 institutions are preparing such applications and might be able to qualify for reopening by Friday if the legislation is enacted. Government sources said, however, that even some of the 20 or 25 strongest institutions might have problems qualifying for federal insurance because their investments do not meet federal tests for savings and loan associations.

Of the remaining 45 or 50 savings and loans, federal sources said, as many as half appear to be so weak that they are beyond salvage. The rest can be saved, the sources said, but someone must absorb losses in their loan portfolios.

One of the original closed institutions, Columbia Savings and Loan of Cincinnati, qualified for federal insurance Friday and was reopened today.

Federal officials familiar with the quick examinations conducted by the Federal Reserve and the Federal Home Loan Bank Board said the problems in the majority of the closed savings and loans predated last week's run and are the result of weak supervision in Ohio.

"Ask yourself, 'Why would a savings and loan opt for private insurance, not federal insurance?' " a top federal legislative official said yesterday. "It's because they don't want the scrutiny of federal examinations or they don't want to face the restrictions on loans and other investments the government puts on federally insured savings and loans."

It appeared that it would take weeks for even the weakened but salvageable institutions to meet federal insurance standards, thus prolonging a crisis that has frozen the assets of half a million depositors. However, legislators would permit depositors to withdraw $750 per month from any savings and loan that remains closed.

State commerce director Kenneth R. Cox told a committee that institutions unable to meet federal standards, or other criteria in the plan, would be forced to liquidate, merge or find new capital.

Ohio has tried to interest large, out-of-state banks in buying the intitutions. Federal Reserve Board officials last week called on several to look at the closed savings and loans. State officials said a dozen out-of-state banks have expressed interest in the closed savings and loan firms.

Sources said three big New York bank companies -- Citicorp, Chase Manhattan and Chemical -- are among them.

But federal rules permit out-of-state banks to purchase only institutions that have assets of $500 million or more. Only one of the closed savings and loans is that big. To attract buyers for the others, the state presumably would have to close a large number and merge them into one or more institutions with $500 million or more in assets.

Bankers said the new institution or institutions would be so loss-riddled that they might not be attractive purchases. Furthermore, they might not be able to get a charter.

Celeste announced his plan late Sunday in Cincinnati, the center of the crisis, after a marathon weekend in which he flew across the state three times for meetings with financial leaders, regulators, legislators and political advisers.

"The purpose of the legislation is to give customers of every reopening association the maximum level of confidence in the institution," said Sen. Richard Finan (R-Cincinnati), sponsor of the bill. "The bottom line is that . . . every bank and savings and loan operating in Ohio will be federally insured."

The bill would give broad powers to the state superintendent of savings and loans and the commerce director, who would be allowed to waive requirements to allow institutions to reopen.

Many legislators greeted it skeptically. "If someone would have introduced a bill like this a month ago, it would have been put away never to be heard of again," said Rep. Robert E. Hickey (R-Dayton).

Aides to Celeste said major Ohio banks gave a cold shoulder to overtures to form a holding company to rescue the S&Ls. "These guys are natural enemies," one Celeste aide said.

The governor declared a "bank holiday" Friday after depositors had withdrawn $600 million from the privately insured institutions the day before. The run was precipitated by the closing of the Cincinnati-based Home State Savings Association after it suffered severe losses in the collapse of a Florida investment firm, ESM Government Securities Inc.

Home State's deposits, like those of the other 70 thrifts, were insured by the Ohio Deposit Guarantee Fund, a private firm, under a $130 million fund. Home State's losses were expected to deplete the entire fund.