The man tipped to be Ireland's first openly gay president said his campaign has been sabotaged by the re-emergence of decade-old remarks about the age of consent and incest.
David Norris, a well-known senator and equality campaigner, accepted his hopes of being one of the world's first openly homosexual heads of state have been badly damaged by the scandal.
Mr Norris, an academic and renowned James Joyce scholar, described as "the lowest blow of all" the resurfacing of an interview he gave 10 years ago, in which he was asked about his views on sexuality.
"I hope all those who are maliciously spreading this inaccurate, misleading misquotation, out of context, I hope they are all deeply ashamed, because they should be ashamed, and I am ashamed of them," he said.
Senator Norris, a frontrunner in the opinion polls, is seeking the backing of TDs (MPs), fellow senators and local authorities to stand as an independent in the race to succeed President Mary McAleese when she leaves office later this year.
The controversy erupted after restaurant critic Helen Lucy Burke, who wrote the original article in Magill magazine, went on the national airwaves to oppose Mr Norris's challenge for the presidency.
Mr Norris said he was "astonished" she chose to do so during this critical stage in his campaign.
"This is an attempt to sabotage my campaign," he said.
"It's a 10-year-old article, there is nothing new and I want to ask why is this being brought up now?"
In the article, Mr Norris is reported as saying: "I cannot understand how anybody could find children of either sex in the slightest bit attractive sexually ... but in terms of classic paedophilia, as practised by the Greeks, for example, where it is an older man introducing a younger man to adult life, there can be something said for it. Now, again, this is not something that appeals to me.
"Although, when I was younger, I would have greatly relished the prospect of an older, attractive, mature man taking me under his wing, lovingly introducing me to sexual realities, treating me with affection, teaching me about life."
But forced to go on RTE Radio's Today With Pat Kenny show to defend himself, Mr Norris said he was having an academic discussion over dinner about ancient Greece at the time.
The word paedophilia should never have been in the interview, as he was talking about "paiderastia" - relations between men and boys - of the ancient Greeks as part of a hypothetical, intellectual conversation, he said.
Mr Norris said some of his answers were clipped and truncated in the published article and he has challenged Ms Burke to made public her tape recording of the interview.
"If anybody is in any doubt, I abhor and condemn the abuse of children, sexual, physical or psychological, and my record shows that," he said.
Mr Norris denied claims by Ms Burke that he had approved the finished article, saying he was shown only two paragraphs and his corrections to those were not published.
"It is a scandal, and it is a scandal that this attempt has been made to sabotage me," he said.
Mr Norris said he had been hurt and grieved by the episode but would press on with his campaign, although he was certain that deliberate damage had been done to him.
The senator said he has consulted his legal advisers and while he was not interested in money, he needed his reputation restored and would go to court if necessary.
Mr Norris said he has been a vocal advocate in the Seanad, Ireland's upper house, and at United Nations level, for the rights of children and women who suffer sexual exploitation.Reuse content