Gay Irish senator David Norris has suffered heavy blows to his presidential bid over a letter of support he wrote for his former partner who was charged with raping a 15-year-old boy.

Mr Norris, who was the favourite for the post, has now lost the support of several backers after the story emerged at the weekend.

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.

Mr Norris has not yet commented publicly. He is expected to hold a press conference this afternoon.

Previously the favourite to win the presidency, he has lost the backing of a number of MPs. He must get the backing of 20 Oireachtas members to stand for the role but at least three of the 14 he has gained so far have dropped their support.

In June, Mr Norris found himself in a storm over comments about paedophilia.

A nine-year-old interview was republished in which he said: ”I haven’t the slightest interest in children, or in people who are considerably younger than me.

“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.”