Updated

New Yorkers and tourists were getting their holiday shopping out of the way Sunday in anticipation of a possible citywide bus and subway strike during the height of the holiday season.

The union has threatened to strike at 12:01 a.m. Tuesday if a deal isn't reached, and it planned a partial strike involving two Queens bus lines Monday.

"We would not strike if there was any alternative, but there is none," a message on the union's Web site read. Commuters should "be aware that all buses and trains may be shut down on Tuesday."

In his weekly radio address, Mayor Michael Bloomberg called a possible strike "reprehensible" and said it would strand commuters and drain $400 million a day from the economy. The nation's largest mass transit system carries nearly 7 million passengers a day.

The transit workers' contract expired early Friday, but the two side agreed to continue talking and the 33,000-member union moved its deadline for a systemwide strike to Tuesday.

The two Queens bus lines, Jamaica Buses Inc. and Triboro Coach Corp., employ about 750 union members and carry about 50,000 riders. They are being taken over by the MTA but are not yet covered by the state's Taylor Law, which outlaws strikes by public employees.

"It is a little unsettling to be the first wave," union officer George Jennings, representing bus maintenance workers, said Sunday. "It's going to be a rough deal. Nobody wants to go on a strike on Christmas."

Commuters said Sunday they had started making plans for a possible citywide shutdown.

"We were very worried when we came down here and heard there was going to be a strike," said Lynne Shapiro, visiting from Amherst, Mass., her arms full of children's books she was buying. "I'm happy to be leaving."

"Let them strike," said Tricia Rettig, who works in corporate finance in midtown Manhattan. "Unions to me are kind of passe."

The last citywide bus and subway strike was an 11-day walkout in 1980. State law allows for heavy fines and lawsuits if public employees strike.

In the contract negotiations, the MTA has offered 3 percent annual raises for each of three years. The union wants 8 percent raises each year. Transit workers make $47,000 to $55,000 annually. The union has also opposed an MTA plan to raise the age at which a new employee becomes eligible for a full pension from 55 to 62.