US Congressional leaders have asked the country's three big car manufacturers to submit a new viable restructuring plan before their request for a multi-billion bailout can be approved.
Senate Majority Leader Harry Reid said General Motors, Ford and Chrysler had failed to convince the American people or Congress that the proposed bailout would be the last.
He said they needed to provide more detail next month of how they would spend the money.
Speaker of the House of Representatives Nancy Pelosi said there was a clear requirement for a new plan.
The heads of the three car manufacturers appeared before a US Senate committee this week in a bid to get a $25bn (€20bn) stop gap loan.
The largest of the three, General Motors, is experiencing severe financial difficulties and faces the prospect of bankruptcy.
Sales are down 45% compared to last year and the company is spending its cash reserves at the rate of $2bn (€1.6bn) a month.
Its Chief Executive Rick Wagoner has said the US economy would suffer a catastrophic collapse if his firm went under.
The US auto industry also maintains that some 3m jobs are on the line because of the crisis.
