It is clear that the downright dastardly Clinton campaign was behind NAFTAgate as a way of derailing Obama's campaign leading up to the Texas and Ohio primaries:
Per the Toronto Globe and Mail, in a story that was the lead on the paper’s front page today, that call to the Canadian embassy was actually from the Clinton campaign, not Obama’s:
“Mr. [Ian] Brodie, [PM Harper’s chief of staff], during the media lockup for the Feb. 26 budget, stopped to chat with several journalists, and was surrounded by a group from CTV. The conversation turned to the pledges to renegotiate the North American free-trade agreement made by the two Democratic contenders, Mr. Obama and New York Senator Hillary Clinton.
“Mr. Brodie, apparently seeking to play down the potential impact on Canada, told the reporters the threat was not serious, and that someone from Ms. Clinton's campaign had even contacted Canadian diplomats to tell them not to worry because the NAFTA threats were mostly political posturing. The Canadian Press cited an unnamed source last night as saying that several people overheard the remark.