A tentative plan requiring businesses within Cambridge to hire a fixed percentage of city residents has been at least temporarily shot down by the city manager.

In a report submitted to the city council last week, City Manager Robert W. Healy called the quota requirement illegal and suggested that the city instead adopt voluntary employment guidelines.

Under the voluntary program, businesses would be asked to cooperate with city officials to inform local residents of job openings.

City Councilor David Sullivan, chairman of the council's employment subcommittee, said this weekend that he is not satisfied with the city manager's new proposal. Sullivan said he will continue to press for a mandatory hiring quota.

"The city manager's report says all the city can do is plead with the businesses in Cambridge for a few crumbs from their table. I don't believe that," Sullivan said. The employment committee will hold a hearing on the voluntary jobs proposal tonight.

Unemployment in the city currently stands at more than 7 percent, with approximately 5,000 residents out of work. The creation of an official employment policy is an attempt by city officials to allow local residents to share in the benefits of the more than $1 billion in ongoing construction projects.

Cambridge officials predict that more than 15,000 jobs will be created over the next 15 years as a result of current development.

A continuing debate centers around the issue of whether the city can set mandatory hiring quotas for qualified Cambridge residents.

An advisory opinion by City Solicitor Russell B. Higley, submitted last week along with the city manager's report, states that a mandatory hiring quota may not be legal.

The Supreme Judicial Court has declared unconstitutional a hiring quota established by the city of Boston for any city-funded construction jobs. The U.S. Supreme Court has agreed to hear an appeal of that decision this fall.

Sullivan said he still believes a city-wide jobs ordinance is possible, especially if the Supreme Court rules in favor of the city of Boston.

The city manager's voluntary plan asks the city council to appropriate $59,000 to establish a city employment service beginning next January. The service would offer job referral and counseling programs, with the possible addition of job training programs at a later date.

Healy also asked for $10,000 from the council to fund an "extensive business survey" in order to determine what kinds of job services the city should provide to meet the needs of expanding firms.

Healy recommended asking county employment officials to operate the proposed Cambridge employment agency.

The Eastern Middle sex Human Resource Development Authority currently aids only a small number of Cantabrigians who fall under certain federal maximum income limits. Under the manager's plan, the city would pay the county office to provide jobs services for all unemployed residents of Cambridge.

Explaining why he is not requesting a more extensive jobs plan, Healy said. "Time is needed to determine whether employers" needs warrant larger investments in training and educational services.