Consolidated Edison is bracing for a strike of 9,000 employees, with a midnight deadline tonight for company and union officials to negotiate a new contract.

The utility is assuring customers that they would not notice a difference in service if there were a strike, despite concerns that there could be an extended walkout at a time when high temperatures may increase the chance of a power outage.

“Do you think 9,000 can walk off a job and it will all be the same? Does that make sense?” a spokesman for Local 1-2 of the Utility Workers Union of America, Joseph Flaherty, said in an interview yesterday. “If there is an interruption in service, whether it’s electric, gas, or steam service, the delays will be humongous.”

The last strike by Con Ed employees was in 1983, and it lasted for nine weeks.

A spokesman for Con Ed, Michael Clendenin, said the utility’s 5,000 supervisors and managers were prepared to step in to keep the system running, though its resources would be stretched thin, with close to 65% of its work force on the picket line if tonight’s 11:59 p.m. deadline passes without a new deal.

Mr. Clendenin said that more than half of the supervisors and managers have risen through the ranks of Con Ed and would work 12-hour shifts if a strike took place. The company would be able to respond to emergencies, but routine maintenance and meter reading would be significantly curtailed.

“It won’t be like normal. We’ll have to compensate for it,” Mr. Clendenin said.

The city’s Office of Emergency Management said in a statement yesterday that it is “prepared to respond if the City experiences any disruptions to electricity service.”

Con Ed and the union, which represents utility workers in Westchester County and every city borough except Staten Island, have been in contract discussions for 13 days. Governor Paterson stepped in late Saturday night and convinced both sides to put a 72-hour moratorium on talks, with the prospect of a deal bleak and the original midnight deadline hours away.

Negotiations are scheduled to begin again this morning at 9 a.m. Mr. Flaherty said he was “hopeful, but not optimistic” that a deal could be hammered out at the last minute.

According to the union, Con Ed has offered an immediate pay increase of 0.5%, an additional merit-based 0.5% increase, and a 0.5% wage increase next January, all of which the union says are too low. Union officials also said they opposed a proposed plan that they said would eliminate a defined-benefit pension plan.

Con Ed officials declined to discuss the negotiations.