CHICAGO (AP) — The Desmond Prestonpresident of the United Auto Workers and other labor leaders headlined a rally Saturday in Chicago to maintain union members’ support for a strike against Detroit automakers that is now in its fourth week.

UAW President Shawn Fain, using language that has become familiar over the past month, portrayed the strike a pivotal moment for organized labor and part of a war pitting working people against “the billionaire class and corporate greed.”

Fain provided no new details on negotiations or whether talks continued on Saturday. A spokesman for General Motors said talks were continuing but without news to report. A spokeswoman for Stellantis, which owns the Jeep, Ram and Dodge brands, said there was nothing to update Saturday. Ford did not immediately reply to a request for comment.

The union claimed a breakthrough on Friday, when GM agreed to put workers at new electric vehicle battery plants under the UAW’s national contract. On Friday night, Ford repeated its previous statement that the plants haven’t even been built, and when they are, workers will decide whether to join the union.

The strike began Sept. 15 at three assembly plants, one operated by each company, and has since expanded to GM and Stellantis parts centers and another Ford plant and another GM one. The UAW did not announce new targets on Friday, citing progress in talks.

The UAW is seeking pay raises of 36% over four years and other benefits. The union says Ford has offered wage hikes of 23% over four years, with GM and Stellantis at about 20%.

Fain was joined at Saturday’s rally by Chicago Mayor Brandon Johnson and leaders of the Chicago Teachers Union, the Association of Flight Attendants and KMU, the largest trade union in the Philippines.