From the FT:
The US and other big trading partners of China are expected to reject Beijing’s latest proposal to join a global pact on government purchases because it does not go far enough in opening the $500bn Chinese procurement market to foreign businesses.
The main concern about China’s latest proposal is that it does not offer foreign companies access to local government and state-owned enterprise procurement contracts, which account for the vast majority of state contracts in China.
Another stumbling block is China’s proposal to only open government construction contracts to foreign companies if those projects are larger than a threshold three times higher than most other major GPA members.
Here's the Chinese offer.