According to a report from Reuters, a Bombardier spokesman said the manufacturer was confident that the U.S. International Trade Commission (ITC), which must affirm the duties for them to take effect, will "reach the right conclusion given that Boeing did not compete for the Delta order."
Mr oleary, while I suspect that the Delta CEO's prediction is right, the reason why might be worth noting. There's another body who gets to review this whole tariff thing. (Delta has lawyers too, and congress-critters whom they can call, just as does Boeing).