Commercial building cleaners rallied in Downtown Manhattan on Thursday and gained supporters across the nation in anticipation of a strike.
As hundreds protested downtown, janitors from 12 cities including Chicago, Boston and Los Angeles signed petitions to honor picket lines, should a strike spread to their buildings.
Contract negotiations continued Thursday in Midtown Manhattan between SIEU Local 32BJ and the Realty Advisory Board.
Office cleaners are threatening to walk off the job if a new deal is not reached once their contract expires this weekend.
"This is kind of a tester, to get the workers ready and to also show the public that this can happen at any time after the contract expires at 12:01 midnight January 1," said one protester.
"We're going to fight this until the bitter end and if the owners don't like it, tough," said another protester.
They are asking for a wage increase to match the cost of living in the city.
Members of the Realty Advisory Board say their expenses and vacancies have gone up and they cannot afford an increase.
A walkout would impact office buildings in in every borough but the Bronx, including the Empire State Building and MetLife Headquarters.