Striking union workers reached a deal on Saturday to return to the job at four downtown Hilton hotels, while bargaining talks appear to have hit a wall with some of the remaining 11 hotels where the work stoppage has entered its fourth week.

Unite Here Local 1 has now approved contracts with 15 of the 26 hotels that were impacted at the height of the strike, which started Sept. 7 and included up to 6,000 housekeepers, servers, cooks and doormen.

“We look forward to welcoming our team members back to work at Palmer House, DoubleTree by Hilton Hotel Chicago Magnificent Mile, Hilton Chicago and The Drake,” a Hilton spokeswoman said in an email.

The union says the new deal will “ensure that hotel workers will keep their health care if they’re laid off in the wintertime” — a main sticking point in negotiations for the striking workers, who have sought year-round health care.

Under the workers’ previous contract, which expired at the end of August, they could be classified as full-time could but still lose benefits if they were laid off during the slow winter months.

“About 3,500 hotel workers are covered by new collective bargaining agreements that guarantee wintertime health care,” union officials said in a statement.

Workers remain in the picket line at 11 hotels, including two Hyatt locations.

Earlier Saturday, Hyatt executives said they had requested a federal mediator to oversee their negotiations with union, who they claimed had “moved backwards in their positions and added new unacceptable proposals” during a meeting on Friday.

“Hyatt continues to negotiate, in good faith with the goal of coming to an agreement. Unfortunately, the union did not share that goal,” Michael D’Angelo, Hyatt’s vice president of labor relations, said in a statement. “Hyatt has agreed to the same wage and benefit increases and extended healthcare that the union has agreed to with other hotels. The union is remaining uncooperative, further demonstrating that it has no desire to reach an agreement.”

A strike is also possible at the Park Hyatt Hotel, the union has said.

Workers are also seeking wage increases and heightened job security, among other benefits.

Most of the affected hotels have stayed open as the work stoppage hit during the tail end of Chicago’s busy summer travel season.

Here’s where the strike continues:
Ambassador Chicago
Cambria Magnificent Mile
Crowne Plaza Hotel Chicago-Metro
Hampton Inn/Homewood Suites Magnificent Mile
Holiday Inn Mart Plaza
Hyatt Regency Chicago
Hyatt Regency McCormick Place
Inn of Chicago
Kinzie Hotel
Warwick Allerton
Wyndham Grand

Here’s where hotel employees have reached new contracts to return to work:
Hotel Allegro
Hotel Palomar
Sheraton
W City Center
W Lakeshore
Westin Michigan Avenue
Westin River North
JW Marriott
Hotel Blake
Millennium Knickerbocker
Ritz-Carlton Chicago
Drake Hotel
Hilton Chicago
Palmer House
Doubletree Chicago Magnificent Mile

Here’s where the union says there “could be a strike at any time”:
Fairmont Chicago
Hotel Raffaello
Park Hyatt Chicago
Tremont Chicago Hotel at Magnificent Mile

Disclosure notice: Some labor organizations have ownership stakes in Sun-Times Media, including the Chicago Federation of Labor. Unite Here Local 1 is affiliated with the CFL.