The U.A.W. Ford vice president, Jimmy Settles, said in a statement: “There is no higher authority than the membership. Through a fair and democratic process U.A.W.-Ford members have delivered job security and strong economic gains for their families and communities.”

With the agreement in danger, Mr. Settles had taken the unusual step on Wednesday of holding a news conference, warning workers that the union was unlikely to get an improved deal if the first one was rejected. He also suggested that Ford could pull back plans to invest $9 billion in the United States.

John Fleming, Ford’s executive vice president for global manufacturing and labor affairs, said in a statement: “This agreement provides a good foundation for Ford Motor Company, our employees and our communities as we work together to create an even stronger business in the years ahead.”

Some Ford workers wanted more.

“In four years, the contract will be null and void, so to me it’s still a two-tier agreement with no cap on entry levels,” said Eric Truss, an employee of Ford’s Dearborn Diversified Manufacturing Plant in Dearborn who voted against the tentative pact with the automaker.

Sharon Bell, who works at a General Motors transmission plant in Warren, Mich., said she, too, had voted against the pact with G.M.

“I’m not excited about it — there’s nothing great about it for the veteran workers,” said Ms. Bell, who said she had worked for General Motors since 1975. “I stopped getting raises over 10 years ago, so you’re not doing me any favors by giving me 3 percent.”

In the case of G.M., the union defended the ability of a minority of its members to hold up ratification. “Since its inception, the U.A.W. has put in place a process to ensure that minority groups have a voice,” the union said.