DETROIT (AP) -- Workers at a General Motors Corp. metal stamping plant in Ohio have threatened to go on strike Thursday in a dispute over local contract issues, a GM spokesman said Tuesday.

UAW Local 549 in Ontario, Ohio, near Mansfield has given the company notice that it will strike at 10 a.m., spokesman Dan Flores said.

The company and local have been negotiating for months over local contract issues, which govern such items as overtime, work rules and job duties.

A message was left for local President Pam Drake.

Local plants negotiate their own operating agreements separate from the national contract, which was settled last year.

The Ontario plant employs about 1,300 hourly workers, according to GM's Web site.

If it occurs, the Ontario strike would be the third against GM over local contract issues.

Workers at a factory in Delta Township near Lansing that makes GM's strong-selling crossovers have been on strike since April 17. A UAW local at another plant in Kansas City, Kan., that makes the popular Chevrolet Malibu mid-size sedan has been on strike since May 5.

Industry analysts have speculated that the strikes are an effort by the UAW to get GM to put pressure on American Axle and Manufacturing Holdings Inc. to settle a bitter 11-week-old strike against the Detroit-based auto parts maker.

GM accounts for 80 percent of American Axle's parts business. About 3,600 UAW workers at five American Axle plants have been on strike since Feb. 26. Negotiations are continuing.

UAW President Ron Gettelfinger has said the threats are about local contract issues and have nothing to do with American Axle.

GM announced Thursday it would kick in $200 million to help settle the American Axle dispute, which has cost GM $800 million and cut its production by about 230,000 vehicles. At times, GM has cut shifts or closed 30 factories due to parts shortages from the strike.

Just before GM announced its payment in a government filing, a UAW local that had threatened to strike at a transmission plant in Warren agreed to a deal. Later Thursday, a local at a stamping plant near Grand Rapids also tentatively agreed on a local contract.