National Party leader Don Brash says if everyone who had thought about adultery backed him he would have a lot of voting support.
Dr Brash spoke candidly on television last night about the affair that broke up his first marriage.
On At Home with Clark and Brash on Prime, Dr Brash, sitting with his wife, Je Lan Lee, said that he had no adequate answer for people who believed he was not fit to be Prime Minister after his affair with her during the 1980s.
"Some do say that. I guess I have no adequate answer to that, and I can't disagree with them ... I can't dispute the facts.
"I guess if all those people who have thought about doing what I did were to vote for me, I would have a substantial block of support among the voting population.
"I remind Je Lan that if we hadn't had that period then we wouldn't have a fantastic 12-year-old son."
A practising Presbyterian at the time, Dr Brash said he was consumed by guilt.
Je Lan said it was a painful time for their families.
"We had been like two trains on a collision course and we caused so much wreckage around us."
Dr Brash said he fell in love with Je Lan at first sight when they met at the Kiwifruit Authority. "Like most men, what first attracted me about Je Lan was her looks, to be frank."
National candidate Paul Goldsmith's biography of Dr Brash, published this year, talked about how the party leader was fascinated by his attractive and highly competent secretary from Singapore.
He began cheating with her, and Lee left her husband in 1983. Brash left wife Erica in 1985. In 1989, he persuaded Je Lan to marry him.
The documentary also featured Helen Clark and her husband, Professor Peter Davis, at home.
The Prime Minister said that in her student days she had been a leather-jacket-clad long-haired moped rider.
She and her husband don't have a dishwasher, a topic that seemed to captivate interviewer Paul Holmes, who also dwelt on the fact that Helen Clark had a habit of heating up old cups of tea in her microwave.