One day after assuring Americans he is not running for president “to make things unstable for the country,” the presumptive Republican nominee, Donald J. Trump, said in a television interview Thursday that he might seek to reduce the national debt by persuading creditors to accept something less than full payment.

Asked whether the United States needed to pay its debts in full, or whether he could negotiate a partial repayment, Mr. Trump told the cable network CNBC, “I would borrow, knowing that if the economy crashed, you could make a deal.”

He added, “And if the economy was good, it was good. So, therefore, you can’t lose.”

Such remarks by a major presidential candidate have no modern precedent. The United States government is able to borrow money at very low interest rates because Treasury securities are regarded as a safe investment, and any cracks in investor confidence have a long history of costing American taxpayers a lot of money.

Experts also described Mr. Trump’s vaguely sketched proposal as fanciful, saying there was no reason to think America’s creditors would accept anything less than 100 cents on the dollar, regardless of Mr. Trump’s deal-making prowess.

“No one on the other side would pick up the phone if the secretary of the U.S. Treasury tried to make that call,” said Lou Crandall, chief economist at Wrightson ICAP. “Why should they? They have a contract” requiring payment in full.

In the same interview, Trump also said this:

“we’re paying a very low interest rate. What happens if that interest rate goes up 2, 3, 4 points? …We don’t have a country.”

Let’s consider these two statements in tandem. Why does the US get a very low interest rate? Because US debt is secured by the “full faith and credit” of the United States. What does that mean? It means that the United States is legally obligated to find someway to pay the debt. What is the quickest way to increase the interest rate by several points? (Well, there is an experiment you can try at home to discover the answer. Don’t pay your credit card bill. What happens to your interest rate?) That would be to tell your creditors that the debt they are buying isn’t guaranteed to be repaid in full.

To put it mildly, the idea that the US government should operate the same way as Trump University is simply appalling. But perhaps it isn’t a surprise given that this is the way Trump has operated.

Trump’s idea for paying back the national debt is basically “Use the bankruptcy laws to further our success!” https://t.co/mEUpmUbJJ4

— Kyle Feldscher (@Kyle_Feldscher) May 6, 2016

And there is a more fundamental problem. The US government runs a deficit most years. Even when it doesn’t run a deficit often issuing new debt to retire older debt makes the most sense. When you tell potential creditors up front that you fully intend to default if the mood strikes you, they become skittish:

But Mr. Trump’s statement might show the limits of translating his business acumen into the world of government finance. The United States simply cannot pursue a similar strategy. The government runs an annual deficit, so it must borrow to retire existing debt. Any measures that would reduce the value of the existing debt, making it cheaper to repurchase, would increase the cost of issuing new debt. Such a threat also could undermine the stability of global financial markets.

In 1979, for example, what the government described as “bookkeeping problems” temporarily delayed $120 million in interest payments. In the aftermath of the delay, investors pushed up interest rates on Treasuries by about 0.6 percentage point, according to a 1989 study by Terry L. Zivney of the University of Tennessee at Chattanooga, and Richard D. Marcus of the University of Wisconsin-Milwaukee. That cost taxpayers roughly $12 billion.

But let’s put aside our disbelief for a second and consider who, exactly would agree to this haircut? The Chinese and other foreign governments? No. Not going to happen. They have no incentive to negotiate. But do you know who would? Social Security Administration and other federal agencies who also hold federal debt.

So Trump could force about half the holder of US debt to renegotiate, but that half would be other US government agencies. To make up the loss from the renegotiation, the US government would have to sell still more debt at a higher interest rate.

This guy is a moron. The US government is not some typical Trump fly-by-night enterprise. Though with Trump in charge it could be come one in short order.