As a follow-up to my earlier post, another issue likely to be raised in tonight’s debate is the issue of federal budget deficits that force us to “borrow from China.” Is this a real problem, and will it hurt if China suddenly decides to stop lending us money?

No and no.

First, rising budget deficits since the Great Recession began have actually been more than financed by rising domestic savings of U.S. households and businesses. In fact, the huge spike in private savings that began in 2007 (see the chart below) is the reason for the Great Recession: households and businesses stopped spending in 2008 and the economy cratered thereafter, cushioned a bit by the rise in government deficits. So, we have not relied on rising borrowing from China to finance the increased budget deficits in recent years, instead the rise in domestic savings has been more than sufficient to cover these.

But what happens if China turns off the spigot and stops trying to buy U.S. Treasuries and other dollar-denominated assets?

This would have two effects. First, the decline in available savings that can be borrowed by American households, businesses, and governments would decline. In normal times, this could bid-up interest rates. Think of interest rates as the price of loanable funds—as the supply of loanable funds falls, the price should be expected (all else equal) to rise. But we’re not in normal times. Instead, the American economy remains characterized by a huge excess of savings over demand for new loans, meaning that there’s no upward pressure on interest rates. Absent this upward pressure on interest rates, no damage would be done if China stopped plowing money into buying dollar-denominated assets.

Second, if China did stop buying U.S. assets, the value of its currency would increase vis-à-vis the dollar, and this would spur U.S. exports, both to China as well as to third-country markets.

So, in regards to China buying the U.S. government’s debt, it’s not only nothing to worry about, it would be better for the U.S. economy if they stopped.