General Motors Corporation plans to close plants and eliminate 25,000 manufacturing jobs in the United States by 2008 in an attempt to restore profitability at the world's largest automaker, its chairman said Tuesday as he fended off calls for his resignation. Chairman and Chief Executive Rick Wagoner told shareholders at GM's 97th annual meeting in Delaware that the capacity and job cuts should generate annual savings of roughly $2.5 billion. About one out of six jobs in the United States will be eliminated, according to a report of the Associated Press.