TIMELINE-UAW workers set to expand strike against the 'Detroit Three' as deal remains elusive

(Updates with latest developments) Sept 20 (Reuters) - A new labor agreement between the United Auto Workers (UAW) union and the Detroit Three automakers remained elusive on the sixth day of the strike. The UAW union launched simultaneous strikes at three factories owned by General Motors, Ford and Chrysler parent Stellantis last Friday. The walkout by some 12,700 workers will halt production of some popular models. The union has said it was prepared to expand the strike to more auto plants if a deal, for which negotiations started in July, is not reached by Friday noon. Here is a timeline of events beginning with the election of the new UAW chief in March: Date Development March 25 Shawn Fain wins the race for the role of UAW president; vows to take a tough stance with the Big Three automakers. July 10 The union says it will open contract talks with Detroit's Big Three automakers starting July 13. July 11 Fain says the union is not afraid to hold a strike at any of the automakers without a fair contract. July 19 Fain meets President Joe Biden at the White House as the union briefed the staff on contract talks with the Detroit Three automakers. Aug. 1 The UAW presents demands to Stellantis, says the union is seeking ambitious benefit increases from the Detroit Three, including double-digit pay rises and defined-benefit pensions for all workers. Aug. 2 The union presents contract demands to General Motors Aug. 3 The union presents contract demands to Ford Aug. 8 Fain angrily tosses contract proposals from Stellantis in a trash can, citing numerous concessions that the Chrysler parent is seeking in labor talks. Aug. 25 The UAW says 97% of voting members were in favor of authorizing a strike at the Detroit Three if an agreement is not reached before Sept. 14. Aug. 31 The union says it has filed unfair labor practice charges with the National Labor Relations Board (NLRB) against GM and Stellantis, saying they have refused to bargain in good faith. Aug. 31 Ford makes a contract offer to the UAW, providing hourly employees with 15% guaranteed combined wage increases, lumpsum payments and improved benefits over the life of the contract Sept. 1 The U.S. NLRB says it will investigate unfair labor practice charges filed by the UAW union against GM and Stellantis. Sept 6 The UAW makes a labor contract counterproposal on economic issues to Ford Sept. 7 GM makes counteroffer to the UAW that includes a 10% wage hike and two additional 3% annual lumpsum payments over four years. Fain calls the offer "insulting." Sept. 8 Stellantis says it offered U.S. hourly workers a 14.5% wage hike over four years but no lumpsum payments. Sept. 8 Fain says the UAW union wants a deal to avoid walkouts at the Detroit Three but expects to go on strike against all of them next week if they do not improve their contract offers. Sept. 11 Stellantis says it plans to make a new counteroffer to the UAW after the union made its own revised offer on Sunday ahead of the expiration of the current four-year labor deal Thursday night. Sept. 13 The UAW rejected counteroffers from the automakers and outlined plans for strikes targeting individual U.S. auto plants in what would be its first-ever simultaneous strike against the Detroit Three. Sept. 15 The UAW launched simultaneous strikes that will halt production of some popular models at three factories owned by GM, Ford and Stellantis. Sept. 16 Negotiators for the UAW and Ford had "reasonably productive discussions" toward a new contract, while officials at Chrysler parent Stellantis said a proposal to resume work at an idled Illinois factory has fallen through. Spet. 18 On the fourth day of the strike, the UAW union said it would announce on Friday more plants to strike if no serious progress was made in talks, adding to pressure on the Detroit Three automakers (Reporting by Ananta Agarwal in Bengaluru; Editing by Anil D'Silva and Arun Koyyur)