Boeing and IAM union leaders are set to resume negotiations on Monday, three weeks after 33,000 workers went on strike.

Two weeks after Boeing Co. tried and failed to end a strike with the brash move of a direct offer to workers, the planemaker and its largest union are taking another stab at a more conventional pattern of consultation and shuttle diplomacy to end the stalemate.

A federal mediator has summoned negotiators for Boeing and IAM District 751 back to a Seattle hotel on Monday. It’s the first inkling of movement toward a compromise that might yield a third contract offer — and the possibility of ending the three-week old strike that’s driving up costs for the manufacturer and its 33,