LAS VEGAS (AP) — Members of a powerful Las Vegas casino workers union and other hospitality workers plan to picket Wednesday outside the Palms casino-resort, where owners have refused to bargain with the union.

The workers will call for Palms owner Station Casinos to negotiate with employees, who voted in April 2018 to unionize.

The company challenged the election’s result, but the National Labor Relations Board determined the company has been “failing and refusing to bargain collectively and in good faith” with the Culinary Union.

The Palms, located west of the Las Vegas Strip, is one of six Station Casinos-owned properties in Las Vegas where workers have voted to unionize in recent years.

The Culinary Union says it represents about 900 porters, food servers, bartenders and other workers at the Palms, which is undergoing a $690 million renovation.

Culinary Union members will be joined by hospitality workers with the union’s national affiliate, Unite Here, which is holding its national convention in Las Vegas.

As part of the dispute, the union in March picketed outside the restaurants of celebrity chefs and business partners of Station Casinos in eight cities across the U.S.

Station Casinos did not respond to an emailed message seeking comment about Wednesday’s planned picketing.

The company, which operates more than 10 casino-hotels in and around Las Vegas, also has clashed with the Culinary Union at its Green Valley Ranch casino-resort in the Las Vegas suburb of Henderson.

Workers there voted to unionize in November 2017. A year later, federal labor regulators found that the company “engaged in unfair labor practices” by refusing to bargain with the Green Valley Ranch employees.