Contract talks will begin again on Wednesday to try to avert a strike by 20,000 commercial building cleaners.
The Realty Advisory Board on Labor Relations, which represents building management, and Service Employees International Union Local 32BJ are trying to reach a new deal by January 1.
Earlier this month, Local 32BJ voted to authorize a strike if a new contract cannot be negotiated.
At issue are wages and benefits.
Union leaders want fair-pay raises, but the Realty Advisory Board says the cleaners are the highest paid in the country.
More than 1,000 commercial buildings in Manhattan, Queens, Brooklyn and Staten Island would be affected by a strike.
Properties that would be affected include the Empire State Building, the Time Warner Center and the MetLife Building.