The move is being seen as another step in the party's process of modernisation.

Archie Norman: "There are very able people (with) different lifestyles"

Conservative Party chairman Archie Norman said the new guidelines were designed to avoid discrimination against candidates who did not have partners and those whose lifestyles were not the norm.

Sir Edward Heath - bachelor prime minister

He also said the wives, or husbands, of prospective candidates should not have to face an interview for a position being taken up by their partner.

Speaking on BBC Radio 4's Today programme Mr Norman said: "In this day and age people expect to go into a selection interview without necessarily having their wife selected as well."

But ultimately, he conceded, it was up to the local party association to chose how it conducted its interviews.

Responding to questions on whether the new guidelines were designed to avoid discrimination against gays and lesbians Mr Norman said: "Our attitude is that of course we respect family values and of course we are a party of the family.

"But equally we respect the fact that there are very able people who not part of a normal family, who have different lifestyles and who can represent their constituency and their country extremely well."

He added: "Politics should be a matter of integrity. It is important that anybody, no matter what their lifestyle background, should be able to represent themselves honestly, and that means being at ease with their own lifestyle."

'Party of marriage'

Not all in the party are happy with the proposals. Dr Adrian Rogers, the Director of the Conservative Family Institute said the Conservative Party is "a party of freedom, family and marriage".

He said: "If you recognise that the personal lives of politicians are incredibly important ... then you have to look at their personal life including their partner.

"And if they haven't, got a partner [you have to be sure] that they are not trying to conceal something."

On the subject of gay and lesbian lifestyles, he said: "I hope that the Conservatives will be quite clear that these deviant lifestyles have no part in the Conservative Party.

"It is not just because one may not like what homosexuals do it is because these people make the laws and that is the difference between politicians and applying to work in a supermarket.

"Their personal lives and the predilections that come with them are vitally important."

Tebbit: Gays should identify themselves

Tory peer Lord Tebbit has urged the government to bar homosexuals from "sensitive" cabinet, such as home secretary.