Gay Irish senator David Norris has pulled out of the Irish presidential race after controversy over a letter of support for a former partner who was convicted of raping a 15-year-old boy.

Three of his supporters – Independent TDs Finian McGrath, John Halligan and Thomas Pringle – all formally withdrew their support today and Mr Norris announced at a press conference this afternoon that he would pull out of the race.

Before the controversy emerged, he was tipped as the favourite for the role. If elected, he would have become the world’s first openly gay head of state.

According to the Irish Times, he told reporters today that he made a “human error” when he wrote a letter on Seanad-headed paper asking the Israeli authorities to show clemency towards his former partner.

He had an almost 30-year relationship with Ezra Yizhak Nawi and the pair remained together for four years after Nawi was convicted in 1997 of the statutory rape of the Palestinian 15-year-old.

In 1998, Mr Norris wrote a letter to Israeli authorities on Seanad-headed paper pleading for clemency for Nawi.

When the story broke at the weekend, it was claimed that Mr Norris and Nawi had separated in 1985.

However, a number of interviews and statements in which Mr Norris said they had met in 1975 and been together for “the best part of 30 years” have now emerged.

“I deeply regret the most recent of all the controversies concerning my former partner of 25 years ago, Ezra Yitzhak Nawi,” Mr Norris said this afternoon. “The fallout from his disgraceful behaviour has now spread to me and is in danger of contaminating others close to me both in political and personal life.

“It is essential that I act decisively now to halt this negative process. I do not regret supporting and seeking clemency for a friend, but I do regret giving the impression that I did not have sufficient compassion for the victim of Ezra’s crime.

“I accept that more than a decade and a half later when I have now reviewed the issue, and am not emotionally involved, when I am not afraid that Ezra might take his own life, I see that I was wrong. He served his time and never offended again.

“Yes, his actions were terrible, but my motivation to write the letter was out of love and concern. I was eager to support someone who has been very important and continues to be important in my life.

“It is very sad that in trying to help a person I loved dearly, I made a human error.”