Once again General Motors is issuing a warning that it may run out of cash. How, you might wonder, considering the billions in taxpayer dollars that have already been pumped into the company? It's unfortunately very simple: GM is still playing catchup with its debt, and all the money spent so far has merely been delaying the process.

Even with $13.4 billion in U.S. taxpayer money in hand, an additional $16.6 billion applied for and another $6 billion expected from foreign governments, GM says it can't afford to repay a $1 billion bond to come due on June 1, according to a regulatory filing snatched up by Financial Times.

The warnings and hints at a possible bankruptcy pervade the documenet filed with the U.S. government as part of its restructuring, and the auditing firm Deloitte & Touche says it has "substantial doubt" about GM's ability to continue operations. Continued operating losses are wiping out any aid funds, while negative shareholder equity and a lack of incoming cash mean the situation isn't likely to change any time soon.

GM itself puts the time frame for any benefit from governmental help beyond the end of 2009, according to this excerpt from their filing: “our efforts to continue to maintain adequate liquidity will be very challenging given the current business environment and the immediate working capital requirements of the viability plan required by the US Treasury loan agreement. Moreover, even if our liquidity enhancing actions are successfully implemented, their full effect will not be realized until later in 2009.”

Sales in February plummeted to their lowest levels since 1967 for GM, off 53.1% versus February of 2008. Even assuming GM gets its house in order and stops hemorrhaging cash to labor and other outlets, turning around the market and its sales figures will prove another challenge, and one that is potentially beyond their ability to control.

Finally laying the matter on the line, GM said of the bond maturing in June, “[it] could also trigger cross defaults in other outstanding debt, which would potentially require us to seek relief through a [bankruptcy] filing."

In an official response to the auditor's findings, however, the company said, "Given GM's public statements on our liquidity position dating back to the end of 2008 and more fully disclosed in our February 17 viability plan submission, the opinion rendered in our 10-K was not unexpected....Once global automotive sales recover and GM's restructuring actions generate the anticipated savings and benefits, the company is expected to again be able to fund its own operating requirements. The auditor's opinion has no impact on the aggressive actions we are taking to restructure our business for long-term viability."