China says that it won't use exchange rate as a tool in trade dispute

Comments by China's foreign ministry

• China won't engage in currency depreciation
• Hopes US doesn't politicise exchange rate issue

In other words, they're pretty much saying that they've not manipulated the yuan to be weaker during the whole trade dispute. Hence, their argument will be that they will not want there to be a currency pledge in the memorandum of understanding as both sides carry on with trade talks tomorrow.