washington u.s. commerce secretary wilbur ross say thursday hop start 90-day countdown clock launch renegotiation north american free trade agreement congress take spring recess end next week ross tell cnbc live interview need leaders house ways mean committee senate finance committee sign notification letter 90-day consultation period start administration send draft letter lay negotiate priorities change think ross tell cnbc letter simply describe broad outline topics discuss think great reason overthink it u.s. commerce 's ross say hop trigger nafta talk countdown next week