The president can spin the press corps and prevaricate all he wants about fiscal responsibility. But math is math. Today we got a taste of what happens when we continually try to offload more and more debt onto the world financial community:

Treasury offered $34 billion worth of five-year notes. Unlike in England, the U.S. sale had more customers than product available.

But the bid/cover ratio — a measure of demand for the Treasuries, which compares the number of bids to the amount of securities sold — fell from 2.21 at the last 5-year-note sale to 2.02 today. This signals weaker demand for Treasuries — at least at the interest rates offered.

The wan demand for today’s Treasuries, and the larger implications, caught traders by surprise.

The United States and most other nations will try to spend their way out of this recession by raising money by selling debt, like today’s auction of Treasuries. This is a fine plan — as long as there is demand for the debt.

If there isn’t, then where will the recovery money come from?

Some analysts, including Art Cashin, UBS’s veteran floor manager at the New York Stock Exchange speaking on CNBC, blamed this afternoon’s stock market dive on the U.S. Treasuries auction.

What this means for the government, and taxpayers, is that the next time the government wants to sell debt, it will have to offer a better deal on the notes, in order to gin up stronger demand.

For the taxpayer, that means more long-term cost.

It also raises a larger, more ominous question: Is there enough money in the world to buy all the debt that governments will require to fund the recovery?

The simple answer is “no.” We will have to inflate our way out or raise interest rates. No teleprompter or talking point is going to help us out of that box.

But that is not all that happened today. At a speaking appearance, Tim Giethner had to be helped by a sympathetic moderator to correct a significant gaffe, in which he suggested that the dollar need not be the principal currency of the world.  No, Tim, we’re not ready to give up on the dollar as the world’s reserve currency. (Pssst: if we did, the Chinese would stop funding our deficit altogether.) Geithner’s remark took the dollar for a dive.

If nothing else, today was an eye-opener.