Supporters of a measure that allows insurance companies to set their own rates before receiving prior approval of the state insurance commissioner rebounded from a setback Thursday and rallied enough votes to pass the bill in the Maryland House of Delegates yesterday.

The measure, which was first enacted in 1984 but must be reaffirmed by the General Assembly this year to continue, passed the House by a 77-to-51 vote. The bill failed Thursday when it fell two votes shy of receiving a majority vote in the House.

Opponents of the measure, who argued that consumers have not reaped the promised benefits from state and federal deregulation of industry during the early 1980s, promised to renew their battle to kill the bill in the state Senate.

"We can do as well in the Senate as we did here Thursday," said Del. Gary Alexander (D-Prince George's), who led the floor fight to force the casualty insurance industry to obtain state approval before imposing new rates, a system that had been in effect for decades before 1984.

Under the law that has been in effect for the last two years, companies offering auto, fire and homeowners' insurance have been able to set their own rates, subject to subsequent reversal by the insurance commissioner if the rates are determined to be excessive.

Del. Casper R. Taylor Jr. (D-Western Maryland), a key supporter of the competitive rating bill, argued that the measure did not constitute a deregulation of the insurance industry, but merely promoted additional competition among the 1,350 carriers of insurance in the state.