I think it will be difficult to impose this on the Americans. They're very protective of their government procurement market—they've demonstrated that. As for Mexico, I doubt it very much, because it has a completely different carbon footprint. In that country, the notion of the environment is not at all as important as it is here.
The example must come from the Canadian government and the way it makes its funds available to the provinces to finance major infrastructure projects. For example, Quebec buys $30 billion worth of goods and services annually. There is a lot of room to use that purchasing power to reduce its carbon footprint.