County Executive Charles W. Gilchrist told Montgomery legislators today that the county may have to delay awarding its cable television franchise as much as two years unless the General Assembly acts quickly to make the county immune from antitrust court suits.

Gilchrist is scheduled to make his long-awaited cable franchise recommendation to the County Council in June, culminating a lengthy, meticulous and expensive process designed to give county officials independent expertise while keeping the process free from political favoritism.

But Gilchrist said today he has been advised by the county's attorney to delay the award unless the legislators pass a bill that would give localities the authority to grant exclusive franchises. The legislation is necessry because of a Jan. 13 Supreme Court decision that makes localities liable for antitrust suits if they award exclusive franchises without state authority,.

Gilchrist's statement today, in an appearance before the county's House delegates, was the strongest indication yet of the seriousness with which Montgomery views the peril to its cable television system because of the Supreme Court decision.

Gilchrist appealed to the delegates to move the bill quickly, noting that there are only three weeks left in this session and it has not been marked as a priority item on the legislators' crowded agenda.

To delay now, he said, would essentially mean to put off until after the fall elections the entire process, including the requesting of bids.. That would delay the final awarding of the franchise for two years, he said.

But the delay, he added, was preferable to a costly antitrust suit, which is possible under the high court's ruling.

Most localities in the state had already been granting exclusive franchises to hand-picked firms, assuming that they were protected from antitrust suits under the state's general blanket of immunity. But when a cable firm sued the city of Boulder, Colo., for restricting its activities there, the Supreme Court decided that localities have no such immunity unless the state specifically grants it to them.