Wales Office Minister Don Touhig is opposing a decision to impose an all-women short-list on the local Labour Party in Blaenau Gwent.
Don Touhig - local party members must have their say
The MP for neighbouring Islwyn told the BBC that he was "against all women short-lists being imposed on a constituency without the consent of local party members".
"The Labour party is a party of volunteers, and imposing changes in this way could damage morale and cause resentment," he added.
Mr Touhig conceded that the Welsh Labour Party had acted properly, and that the Welsh executive had no choice but to follow rules passed at conference at an UK level.
He also said that he supported all-women shortlists in principle, but in Blaenau Gwent local party members had to have their say on the nomination.
Local MP Llew Smith has announced that he will stand down at the next election and said any attempt to impose an all-woman shortlist on his local party would be resisted.
Mr Smith stressed: "This is not about positive discrimination. This is about politics.
"What's ironic is that if this system had been in operation when my predecessors Nye Bevan and Michael Foot had been seeking nomination, they wouldn't have been able to apply for their positions."
When asked what the Blaenau Gwent party would do to oppose any decision in favour of all-women shortlists, Mr Smith said: "I find it hard to imagine that they are going to sit back and accept that decision."
Llanelli MP Denzil Davies has also decided to stand down at the next general election.
He said his constituency party would also want to choose its own candidate and not have an all-women shortlist imposed on it by the Labour Party Wales.
"The local party will want to choose its own candidate and would be upset if not allowed a choice," he added.
Cardiff North MP Julie Morgan, who is in favour of all-women shortlists, said their adoption was needed to end a situation in which just seven female MPs have ever represented Welsh seats.
Julie Morgan - need for more women MPs
Mrs Morgan said: "Women are 50% of the Labour Party (but) there have only been seven women MPs in Wales in the whole history of the vote."
There are currently four women MPs out of 40 in Wales.