DETROIT (AP) âÄî A person with knowledge of General Motors’ plans says Rick Wagoner will step down immediately as chairman and chief executive of the struggling Detroit automaker. The person asked not to be identified because Wagoner’s plans have not been formally announced. The move comes on the eve of President Obama unveiling his plan to reinvigorate the U.S. auto industry. Obama and other administration officials have said they would demand deeper restructuring from General Motors Corp. and Chrysler LLC before they would get any more government loans. Both companies are living on a total of $17.4 billion in federal aid.