All I can tell you is that Canada Customs' policy for entry into Canada is a follows: you need a passport, OR proof of citizenship (usually this consists of an ORIGINAL of a birth certificate) and a photo ID. So you can see there is no official need for a passport. I would think it prudent to get one anyway, as they are the easiest way to show your citizenship. I understand that many airlines require that you have a passport to fly international flights. As far as TSA demanding a passport, as far as I know they have no jurisdiction whatsoever concerning customs/immigration.. and certainly NOT into Canada!
Hope this helps?