The nation's largest public transit system, moving more than 7 million people daily throughout New York City, could come to a screeching halt next week if a new union contract is not reached.

A threatened walkout by 34,000 bus and subway workers has forced the city into a hodgepodge of back-up plans that call for people to use car pools, share taxis, hop on ferries and walk. A strike would be the first in 22 years and threatens the city's already-fragile economy.

"We will not be cowed," declared Mayor Michael Bloomberg, who said he would bicycle to work if his usual subway line is shut down. "We will take advantage of every legal remedy and we will not let anybody stop this city from going forward."

With the current Transport Workers Union contract expiring on Sunday, the final days will likely be marked by maneuvering at the negotiating table and in the courts. Even though state law prohibits walkouts by public employees, union members have already authorized their leaders to call a strike for Monday.

The two sides differ on money. The Metropolitan Transportation Authority, the state agency that runs the system, has offered no raise in the first year and has tied raises in subsequent years to productivity increases. The union is seeking a 24 percent increase over three years.

Union leader Roger Toussaint said Tuesday the two sides were "continents apart." MTA Chairman Peter Kalikow offered no optimism, but said, "my experience in collective bargaining has taught me that you never give up, you always sit at the table."

A walkout of even a few days could cause lasting damage to the city's economy, said Anthony Sabino, an attorney and professor at St. John's University in Queens.

With the city suffering from the Sept. 11 attacks, the national economic downturn and massive government deficits, Sabino said a strike in the midst of the tourist-rich holiday season "couldn't come at a worse time."

Bloomberg estimated the city would lose anywhere from $100 million to $350 million a day, from the costs of police overtime to losses in holiday business revenue.

"A strike would devastate our economy," he said. "A strike would sabotage the Christmas shopping season."

The state's Taylor Law prohibits public employees from striking. Both Bloomberg and Gov. George Pataki have said that in the event of a strike, the government would respond forcefully by seeking an immediate court injunction and heavy fines from both the union and its individual members.

The city's contingency plans would allow taxis to pick up several fares, increase ferry routes, and require that passenger vehicles carry at least four people to enter or leave Manhattan on weekdays.

Jeanette Greenwell, 30, who commutes each day from the Bronx to her job in midtown Manhattan, was worried about her options.

"I guess I'd have to walk across the Triborough Bridge, or maybe buy a bike," Greenwell said. "I could maybe afford a cab for day or two, but that's it."

Anna James, toting four shopping bags at a Manhattan subway station, said she would change her holiday shopping plans. "I'm going to have to finish my shopping before Sunday," she said, "and after that I'll just keep my fingers crossed."

The city had two earlier walkouts — in 1966 and in 1980, when then-Mayor Ed Koch personally exhorted New Yorkers to walk to work.

"Every day at the bridges connecting Manhattan with the other boroughs, I showed up for an hour in the morning and an hour at night encouraging people to walk to work," Koch recalled.

But the 1980 strike was in April. This is December, with freezing temperatures and the chance for snow.

"People are not going to walk from the Bronx to their jobs in midtown Manhattan," said Sabino, who suggested the timing gives the union some advantage in negotiations.

Legal action to prevent strikes has been taken in other years, although an MTA spokesman declined comment on current plans.

In 1999, the MTA obtained a restraining order against a strike by the union. The union would have faced an initial fine of $1 million — with that figure doubling daily — had it violated the order.

The MTA is run by a 17-member board predominantly appointed by Gov. George Pataki, but Pataki has operated largely behind the scenes so far.

A growing number of politicians have called for Pataki to take a more visible role in the talks, noting that he is the most powerful individual involved in the issue. For now, though, Pataki said he is confident his appointees will find a resolution.

"I'm not going to undercut the process," the governor said. "I have tremendous confidence in the MTA and their professionals."