Trump is and always has been a one-trick-pony: Shock and awe with a ridiculously over-the-top threat to shake his opponent and anchor the discussion high, then "accept" a deal that's better than any that could have been achieved with a calm opponent (pure bullying).

His second weapon is throwing a monkey wrench into the works after agreeing to something. Keep the opponent on their back heel.

It works well, until it doesn't. Once you meet an opponent who stands firm no matter what you threaten, you lose your bargaining position. Carney is well-versed in this kind of negotiation.