Former Welsh Conservative chairman Sir Eric Howells says he would support an unofficial Tory candidate in May's assembly election.
Sir Eric Howells is a life president of the Welsh Conservatives
He says members from outside have taken over the Carmarthen West and South Pembrokeshire party, and he and others would back an unnamed rival candidate.
But Tories called them a tiny minority, and they would not let members with "bruised egos" undermine efforts.
The previous candidate resigned last March over comments on homosexuality.
Sir Eric said a group of Conservatives connected to a pro-hunting organisation were responsible for selecting former candidate John Jenkins' replacement, Angela Burns, and taking over the association.
Sir Eric claimed the vast majority of Tory branches in Carmarthen West and South Pembrokeshire want a different candidate and one will announce his candidacy "within weeks".
Speaking on BBC Wales Dragon's Eye programme, Sir Eric said: "When he announces it, hopefully this candidate that we have now will stand down and let him have a free run at winning the constituency."
John Jenkins was forced to stand down over 'anti-gay' remarks
Sir Eric, life president of the Welsh party, said that if Ms Burns did not stand down "we'll have to support the new candidate because after all he is the one that the majority of members want".
Former Tory spin doctor Matthew Gunther-Bushell said it was extraordinary that someone of Sir Eric's experience and long service could back an alternative candidate.
Mr Gunther-Bushell said: "It should be a winnable Conservative seat.
"It could theoretically cost them the election."
A Welsh Conservative spokesman said: "A tiny, isolated minority in the constituency appear to prefer fighting members of their own party rather than the opposition.
"We will not allow members with bruised egos to undermine our efforts to win this seat at May's assembly elections."
The spokesman denied that any organisation had "taken over" the local association and said there were clear rules preventing this.
For his part, Sir Eric said he was sad that people in the party were accusing him of having a bruised ago and there was no truth in the suggestion.