Trump so-called 'tweaks' include U.S. companies able to get into Canada public sector services. This is not a tweak. This is an entirely new type of trade. 

NAFTA deals with trade of goods only, not services. (CETA deals with goods and services)

Trump is trying to pull an American CETA under a tweaked NAFTA. Not going to happen without Canada voters give Trudeau a mandate to do a new trade agreement with the U.S. Not going to happen without U.S. states agreeing to let Canada bids on their public sector services. That's 50 states agreeing my friend. 

And why should Canada open up its public sector services to U.S.? Trump proposal is a no-go.