I believe, from the U.S. perspective, that they were, in fact, supportive of eliminating withholding tax on interest because of the benefits it would provide their investors, as it would, conversely, ours. An incidental effect of that is that it would actually have allowed Canadian firms to invest in the U.S. from Canada and also from some third countries. But I don't know that the U.S. perceived that to be an issue for them, one way or the other.
On May 15th, 2007. See this statement in context.