Next the union will try to reach a new deal at Ford Motor, which also has more than 50,000 UAW members at its USA plants.
The tentative deal with the United Auto workers covers 53,000 union employees at 22 of Ford's assembly and parts plants.
"The agreement, if ratified, will help lead the Ford Motor Company, our employees, and our communities into the future", read a statement from the company.
The UAW said in a statement Friday that it will hold meetings with skilled trades members at each plant to determine "what reason(s) they had for rejection of the tentative agreement". GM's hourly work force of 52,700 has until Saturday to cast their ballots.
Fiat Chrysler workers approved their contract last month.
CHATTANOOGA, Tenn. (AP) - Attorneys for Volkswagen's lone US factory in Tennessee on Tuesday argued against efforts by maintenance workers, who make up 12 percent of blue-collar workers at the plant, to seek a union election.
Workers at two union locals at a huge factory in Lordstown, Ohio, east of Cleveland voted overwhelmingly for of the deal on Friday.
The close vote has surprised auto industry observers, including Art Schwartz, a longtime GM negotiator, and president of Labor and Economics Associates in Ann Arbor, Mich.
Overall 55.43% voted for the agreement; 44.57% voted against the agreement.
To note, GM paid an average of $9,000 to the average UAW member in profit sharing in 2015 alone, according to the Center for Automotive Research.
He said he's hoping the deal would secure products and jobs in the United States.
The sources wished to remain anonymous because the union and company have not released details of the proposed contract.
There are between three and four production workers for every skilled trades job, and a majority of production workers are voting yes. All in-progression employees are moved to traditional health care plan.
"They're telling the second-tiers they are going to get up to top pay in eight years, but in four years with the next contract that could all change", said a worker with 15 years.
And a two-tiered wage system would phase out in the next eight years.
Several workers told WSWS reporters that they felt outraged by the fact that only 4,000 workers were being offered retirement incentives although 20,000 are eligible to retire.