Workers at dozens of the city’s top hotels — including the Palmer House and Sheraton Grand Chicago — voted on Wednesday to authorize a strike later this month as they fight for a new collective bargaining agreement.

The employees will hit the picket lines if a new deal is not struck by Aug. 31, after Unite Here Local 1 members voted “overwhelmingly” — more than 90 percent — in favor of a potential strike, a union source said late Wednesday.

Thirty-one hotels, most of them downtown, would be affected by the work stoppage. The exact number of hotel employees potentially involved in a strike was unclear, though one source put it in the thousands.

Unite Here representatives did not return messages seeking comment.

The potential strike comes as the summer travel season winds down, and could deal a significant blow to downtown businesses. In addition to pay, key points in collective bargaining talks include job security, pensions, year-round health insurance, sick days and overwork.

As workers filed into Orchestra Hall Wednesday afternoon to cast their votes, a Chicago Sun-Times reporter and videographer were barred from the building, with one of the organizers saying, “It’s a private event for our members.”

“We’re tired of being stepped on, when these billion-dollar corporations are getting all this money and then they forget us,” said Larry Lewis, 39, a housekeeper at Palmer House. “They forget that we’ve made these places five-star, world-wide-class hotels. …. They want to take our healthcare, they want to take our medicine.”

Lewis — who has worked at Palmer House for 18 years — makes approximately $20 an hour and, he says, currently pays low healthcare costs. But he’s worried his employers are trying to shift much more of the burden for healthcare costs to him and his fellow workers.

“Imagine with kids and you have to pay a lot of healthcare,” said Lewis, a father of five. “So now how are we supposed to make our situation better if we can’t afford decent health care?”

In a video on the union’s web site, workers complain about being overworked, about department cuts and health insurance that’s not available year round. At the same time, “Business is booming. Fifty-five million tourists came to Chicago last year. In 2017, Chicago hotels made over $2 billion,” the employees say in the online video.