To specify the argument, I think Edwards is the one most likely to succumb to pressure from special interests (labour organisations and industrialists) to raise tariffs, and you can't easily raise tariffs just on China, you have to raise them across the board.

The EU will not like tariffs.

On the other hand, I like the potential an Edwards presidency offers to rearrange the institutions and terms of international trade. But we'd have to form a common understanding to do that, and it's crucial do so very early in his eventual presidency.