The outspoken attack by Mr Hitchens, known for his strident opinions in The Express, follows the former defence secretary's admission of homosexual experiences while at university.
Mr Hitchens wrote in The Spectator: "Like so many of his generation, I would guess he [Mr Portillo] does not much like this country as it is now or recently was, and wants to turn it into somewhere and something else. I think homosexual acts are wrong. However, having done many seriously wrong things myself and fearing I will do many more this side of the grave, I cannot believe that this is a political issue or even my business."
But both men will have to fight off Rupert Allason, the former MP and spybook writer Nigel West. A close ally said Mr Allason was a "strong local candidate who has lived in the constituency since he was one year old". The left wing of the party plans to put forward a "stop Michael" candidate because of his arch Euroscepticism, although insiders say they have yet to find someone high-profile enough.
The constituency's Conservative Association meets today to decide a selection process timetable. Central Office has not named a by-election date.Reuse content