Less than a day before celebrities were set to arrive at the Metropolitan Museum of Art for the Met Gala, the union representing employees of Vogue and other Condé Nast publications indicated that its members were ready to walk off the job on Monday over contract negotiations, potentially snarling the biggest night of the year for the magazine and its editor in chief, Anna Wintour.

In a vocal in-person and social media campaign leading up to the event, which is co-hosted by Ms. Wintour and costs $75,000 per person, the Condé Nast Union pledged to continue to take action as needed to bring the publisher to the bargaining table. In a post on X, the union warned on Saturday night that management could “meet us at the table or meet us at the Met on Monday.”

The threat of a protest at what is sometimes called “fashion’s biggest night out” comes after over a year of bargaining for union members to create their first contract. In addition to establishing just cause as the basis for firing employees, the organizers are hoping to avoid layoffs proposed in November that they said would affect 17 percent of union members, or nearly 100 employees.

In addition to Vogue staff members, the Condé Nast Union represents employees from titles including Vanity Fair, GQ and Architectural Digest. (The New Yorker, Pitchfork and Ars Technica maintain their own unions and contracts.)

In January, the Condé Nast Union held a one-day work stoppage. Now, many of the union’s approximately 540 members have turned up the pressure, which could potentially culminate in picketing at the Met Gala. On Wednesday, union members participated in a May Day rally at Condé Nast’s headquarters at One World Trade Center in Manhattan. Later that week, staff members also covered Ms. Wintour’s neighborhood in fliers reading “Anna Wears Prada, Workers Get Nada,” taping them to lampposts and slipping them under windshield wipers.