Detroit ? Contract negotiations between General Motors Corp. and the United Auto Workers reached a critical point as local union officials hoped for an agreement but prepared once again for a possible strike today.

Leaders at factories across the country received conflicting reports out of Detroit Sunday afternoon. Several reported progress and optimism but said that if no agreement was reached Sunday night, the union would walk out this morning.

A local union in Arlington, Texas, told its members to report to work as scheduled today but said it was committed to a strike if necessary. In a joint statement sent to union members and the media, UAW Local 276 leaders told members they expected negotiators either to wrap up talks or declare an impasse at the end of Sunday’s negotiating session.

“We understand the issues are complex and the effects far-reaching,” President Enrique Flores Jr. and Shop Chairman Dwayne Humphries said. “Solutions are certainly proving to be difficult.”

At a union meeting Sunday afternoon, UAW Local 735 President Chuck Rogers told members from a GM transmission complex near Ypsilanti that he was told by one of the negotiators that if no agreement was reached Sunday, they will go on strike.

Two other local leaders also said they were told to expect a strike if no agreement was reached Sunday. They asked not to be identified because the talks are private.

Negotiations continued past midnight into this morning, said GM spokesman Dan Flores.

GM’s contract with the UAW was to expire at midnight Friday, but the union extended it on an hour-by-hour basis. The strike threat loomed until early Saturday, when negotiators told local leaders to stand down.