Elizabeth Truss was selected as a candidate last weekend
Conservative party members in Norfolk are "irritated" they were not informed that their general election candidate had had an affair.
Elizabeth Truss was selected as the Conservative candidate for South West Norfolk on Saturday 25 October.
Newspaper reports subsequently focused on an extra-marital affair she had with a Conservative MP four years ago.
Hugh Culver, of the South West Norfolk Conservative Association, said members should have been told about it.
Conservative leader David Cameron backed Ms Truss, who now faces another meeting of the local party to decided whether she will be de-selected, saying the affair had been made public some years ago.
But Mr Culver, deputy chairman of the association, said: "What we don't like is that we were not told by the party. People think they should have been told.
"They felt they were made fools of because they chose this candidate and the next day it was all over the (news) that she had an affair."
He did not ask Ms Truss, or any of the other prospective candidates, whether they had any skeletons in their closet as they had already been through a rigorous selection process to get to this stage, he said.
A Conservative party spokesman said: "We cannot comment on private meetings or the selection process. Elizabeth Truss has been open and honest at all times and is an excellent candidate who has our full support."
The association will meet in two or three weeks to decide whether Ms Truss should be de-selected, Mr Culver said.