hampshire poll of 2020 hopefuls shows joe biden, bernie sanders, and elizabeth warren leading. but they're all within the poll's five-point margin of err error. also the poll shows a lot of uncertainty, 64% of people, very high number, saying they're undecided. >> still very early. president trump says the u.s. will block sales of f-35 stealth fighter jets to turkey, after turkey received a new air defense system from russia. >> because they have a system of missiles that's made in russia, they're prohibited from buying over 100 planes. >> the president turning to a familiar tactic, blaming the obama administration for the situation which could affect turkey's membership in nato. let's bring in our reporter live from istanbul with the latest. good morning. >> reporter: good morning, dave. for months, u.s. officials have