A businessman who co-chaired Donald Trump's New York campaign has said he wants to see US president Barack Obama die from mad cow disease and the first lady "return to being a male".

The failed Republican gubernatorial candidate Carl Paladino made the comments in response to a survey by Artvoice, a Buffalo newspaper.

The publication asked local artists, performers and business owners for a New Year's wish list.

In his response, Buffalo businessman Mr Paladino wrote that he hopes the president dies from a disease caught from "having relations" with a cow.

He said he wants to see Michelle Obama "return to being a male and let loose in the outback of Zimbabwe where she lives comfortably in a cave with Maxie, the gorilla".

Mr Paladino confirmed by phone and email that he wrote the comments.