If Canada specifically isn't willing to do it first, it wouldn't help the chances, that's for sure.
But I think the bigger question, to be absolutely honest, if we're going to deal with the global real world of realpolitik is whether the United States is going to be willing to take the lead and whether Canada will be a part of that, in consenting to do it, or not.
To be absolutely blunt about this, if at the end of the day Canada says, we're uncomfortable taking the lead without developing countries doing so, but the United States says it is, what is essentially going to happen is they're going to go ahead with it and say to Canada: you made that decision; you're outside of this process.
Canada, as part of the North American contribution to this, can play a critical role. I think it really needs to be accentuated, because it has to be much clearer about how it's planning to take that lead, how this 20% is going to be achieved. That all needs to be much further elaborated for them to have any kind of credibility.