China owns, by most accounts, the largest pool of U.S. Treasuries in the world. It continues to buy them, helping the U.S. to fund its growing deficit. If China exits the market as a buyer, the interest rate that the U.S. has to pay for its debt would rise substantially.
Hillary Clinton is hoping to keep China buying U.S. debt. She did a little begging in the most populous country in the world. According to Bloomberg, Clinton used a bit of circular reasoning in her argument to have China remain a big buyer. "China knows it needs a healthy American economy as its biggest export market, she said, adding that the U.S. must take 'drastic measures' to stimulate growth."