Rattner’s decision to step down after fewer than five months on the panel follows the administration’s successful plan to march GM and Chrysler through what Rattner once called “quick rinse” bankruptcies, backed by government aid that totals $85 billion. Rattner also carried out the firing of former GM Chairman Rick Wagoner as part of the government’s rescue.Steven Rattner, the Wall Street financier who drew the Obama administration’s road map for guiding General Motors Co. and Chrysler Group LLC through bankruptcy, will resign from the president’s auto task force, the administration said Monday.The exact date of Rattner’s departure hasn’t been determined. The Treasury Department said Ron Bloom would oversee the auto task force after Rattner leaves. Rattner declined to comment. Steven Rattner stepped down Monday after having overseen the U.S. government’s unprecedented efforts to restructure General Motors Co. and Chrysler Group LLC