What is said above is correct..When you are taking PM as Prime Minister ( singular), usage of 'Has' is correct. But when it's regarding a group like Project Managers (plural), usage of 'Have' is right.

It's all about whether it has been referred to a single person or to a group.if plural use 'Have' and if singular  use 'Has' that's it.

Eg: Mr. Jack has Mercedes Benz car (singular)

    The people who  always blame others do not have time to improve themselves (plural)