Sen. Alan K. Simpson (R-Wyo.) has prepared a revised immigration bill that would delay amnesty for illegal aliens already in the United States until a presidential panel certifies the effectiveness of proposed sanctions against employers who hire undocumented workers.

The new bill, which Simpson plans to unveil this week, is designed to overcome objections that derailed his sweeping effort to revise immigration laws in the last days of Congress last year.

There are indications that Hispanics will oppose the new measure even more strongly, since it delays their principal goal of legalizing the status of aliens here for years.

The new measure, a copy of which was obtained by The Washington Post, largely resembles the hotly contested bill on which he and Rep. Romano L. Mazzoli (D-Ky.) worked for two years to push through the 98th Congress.

The revised bill, which Mazzoli is not cosponsoring initially, retains the basic elements of employer sanctions and legalization of aliens.

But, according to its draft, the president would be directed to appoint a "legalization commission" to determine whether the bill's sanctions against employers are working.

The panel would report one year after the law takes effect, and no legalization of aliens could occur until the panel certified that the sanctions were working.

Senate sources said the change reflects Simpson's view that neither Congress nor the public will support amnesty until persuaded that new aliens are not crossing the border and taking jobs that could be held by Americans.

Simpson will tell Hispanic groups that they have no hope of achieving legalization for aliens unless they agree to this delayed approach, the sources said.

Once sanctions are ruled effective, the Simpson bill would grant temporary legal status for two or three years to aliens who have lived in the United States since before 1980.

After that, they would be granted permanent legal status if they demonstrated minimum competency in English. Last year's bill granted immediate amnesty to longtime alien residents.

The new measure would increase criminal penalties on employers who knowingly hire aliens, bring them into the country or are involved in use of altered identification documents. Civil fines would range to $10,000.

In another change, Simpson would ease paperwork requirements on firms hiring foreign nationals. But business groups are likely to remain opposed to making companies criminally liable for their foreign employes.

Another portion of the bill would provide increased funding for border patrols by the Immigration and Naturalization Service and for Labor Department enforcement efforts. It would establish special procedures to bring seasonal agricultural workers into the country and establish a second presidential panel to review those procedures.

Simpson has circulated about 20 draft copies of the bill to interested parties in an effort to build support for his revised approach.