Michael D Higgins, the Labour candidate, has raised concern that Martin McGuinness is using the presidential election to "rationalise" and "endorse" the Provisional IRA campaign of terrorism.
n a strategic intervention, Mr Higgins - one of the two clear frontrunners - has also told the Sunday Independent that it would be "quite wrong" for Sinn Fein to "claim ownership" of the peace process for "electoral purposes".
He said there was a "clear conflict" between accounts given by Mr McGuinness of his "paramilitary career" and information available to successive Governments.
"Irish people want a President who will be honest and open... I believe it would be helpful if the conflict over different accounts was faced up to and answers given," he said.
Mr Higgins said that he, personally, was "absolutely and unequivocally opposed to the campaign of violence carried out by the IRA" and highlighted his "political opposition" and "personal revulsion" at that violence.
On the IRA campaign of violence, he said: "I would be particularly concerned if this presidential election campaign was to be used to seek some sort of rationalisation of or endorsement for that campaign."
In what was last night interpreted as vindication of the strategy to highlight the terrorist past of Mr McGuinness, the former Labour minister added that he expected the electorate would "want to consider not just the recent record of Martin McGuinness but also his record overall".
Mr Higgins made his statement in response to a series of questions asked of each candidate by the Sunday Independent following a controversial RTE Prime Time presidential debate last Wednesday.
A Sunday Independent/ Quantum Research nationwide poll has found that an almost two-thirds majority (63 per cent) believed Miriam O'Callaghan, who hosted the debate, was justified to ask Mr McGuinness how he squared his religious belief with his involvement in IRA murders.
The clear, decisive and timely statement from Mr Higgins, on an issue which has come to dominate the election campaign, stands now in marked contrast to the position of the other frontrunner, Sean Gallagher.
In response to the same questions posed by the Sunday Independent, Mr Gallagher said: "I do not like 'condemning' people... I wouldn't like to politicise grief. My campaign has always focused on my strengths as a candidate, not the weaknesses or perceived weaknesses of others."
Our poll, which was taken last Friday, and excluded 'Don't Knows', shows: Mr Higgins (36 per cent); Mr Gallagher (29 per cent); Mr McGuinness (13 per cent); David Norris (10 per cent); Gay Mitchell (6 per cent); Mary Davis (4 per cent); Dana Rosemary Scallon (2 per cent).
Mr Higgins's decision to definitively state his position on the central issue of the election was last night described as "interesting" by a source close to the Fine Gael candidate, Gay Mitchell.
Mr Mitchell had been criticised by some Fine Gael strategists, and by elements of the media, notably RTE News, for his decision to draw attention to the terrorist background of Mr McGuinness.
Last night, the source close to Mr Mitchell said: "What Michael D is rightly doing now is a vindication of Gay and of those who agreed with him and argued in favour of asking Mr McGuinness about specific crimes committed while he and Gerry Adams directed Provisional IRA operations."
The Sunday Independent questions to the candidates arose from an assertion by the former Garda Commissioner, Pat Byrne -- who spent much of his career in anti-subversive units until his retirement in 2003 -- that Mr McGuinness was a senior figure in the Army Council of the IRA.
In large part, the questions were also based on specific acts of terrorism by the IRA.
In response, Mr Norris, another independent candidate, in his first statement on the issue, said that Mr McGuinness must accept a level of responsibility for the killing of Detective Garda Jerry McCabe.
Asked if the Sinn Fein candidate bore a "moral if not direct responsibility" for the killing, Mr Norris said: "I believe that if you are at the leadership of an organisation, even though you may not have given specific commands in specific instances just. . . that responsibility does exist in this case."
On this issue, Mr Gallagher said: "The former Garda Commissioner may be privy to information not available to me so I am reluctant to comment on a matter on which I do not have information."
Mr Mitchell answered affirmatively to the questions, and added: "Mr McGuinness would not be made minister for defence if Northern Ireland had a sovereign government. I do not believe he should be given the position of supreme commander of the Defence Forces in this State."
It is the intervention this weekend of Mr Higgins on the Provisional IRA campaign of violence, however, which is expected to prove crucial as the election enters its final full week.
Mr Higgins also said that Mr McGuinness had "met the constitutional requirements for nomination", so he was entitled to be a candidate in the election.
He said he personally had "acknowledged the need for courageous steps to end the conflict" in the North.
"In this regard as minister with responsibility for broadcasting, I took the decision to end the ministerial directive under Section 31 of the Broadcasting Act, which banned appearances on the airwaves by members of Sinn Fein and a number of other organisations," Mr Higgins said.
"My decision, which was based on my confidence in the judgement of the public, was strongly criticised by some people at the time, but I believe that it contributed significantly to creating a climate where peace was possible."
He added: "I am particularly proud of the role played by my then party leader, Dick Spring and by John Hume and the many other members of our sister party in Northern Ireland, the SDLP."
Mr Higgins concluded: "I believe that people are capable of change and I accept the statements made by Martin McGuinness that he has rejected violence and that he is committed to democratic politics.
"In this context, a clear statement from him condemning such incidents as the murders of Detective Garda Jerry McCabe and Private Patrick Kelly and Garda recruit Gary Sheehan would undoubtedly help reassure the public."
Independent candidate Ms Davis said: "The candidates in this race are valid as they have entered the race in an entirely democratic way through the nomination process laid out in the Constitution.
"All of us are subject to a high level of scrutiny over the course of this campaign, and this is right and proper as the choice that is before the people is an important one.
"When the vote takes place later this month, the public should have all of the information that they need before them in relation to each candidate so that they can make an informed choice."
There was no response from Ms Scallon.