Fianna Fáil minister Darragh O’Brien has said Conor McGregor would “not be fit” to become president of Ireland.
The transport minister said that he does not envisage a situation where the former MMA fighter will get the backing of enough politicians to get on the ballot paper.
To enter the race to replace President Michael D Higgins, a person must receive either 20 nominations from members of the Oireachtas, TDs and senators, or four county or city councils.
In recent days, Mr McGregor set up a petition seeking people to express their wish for him to be on the ballot paper.
The Sunday Times reported that Mr McGregor is considered a legal challenge to the eligibility rules.
Speaking at the opening of Woodbrook Dart station in Shankill, south Dublin, Mr O’Brien said: “Like any citizen, he’s entitled to take a case, should he wish, but the constitution is clear on that.
“The nomination process is clear. I don’t envisage he’ll be nominated to run for president.
“I think it’s open to any citizen to take a challenge, should they wish.
“But the office of Uachtaráin na hÉireann is the highest office in the land. It’s a critically important office.
“If you look at the work that Michael D Higgins has done over the last 14 years and representing our country abroad with such distinction, I would just ask people to draw the comparison to what our president has done and what someone like Conor McGregor might do.
“I don’t think he would be fit to hold that office.”
Earlier this month, Mr McGregor lost his appeal against a civil jury finding that he assaulted Nikita Hand in a Dublin hotel in December 2018.
In a civil case heard last November, she alleged that Mr McGregor raped her in a Dublin hotel in December 2018, and she sued him for damages.
Mr McGregor denied the allegation and said that they had consensual sex.
A jury found McGregor had assaulted Ms Hand and awarded her €250,000 in damages. He was also ordered to pay Ms Hand’s costs in the case.
To date, in the contest for the presidency, Fine Gael’s Mairead McGuinness and Independent TD Catherine Connolly have been declared as candidates and have sufficient backing to secure a place on the ballot paper.
Separately, businessman Gareth Sheridan has declared his bid to become an independent candidate.
Aged 35, he would be the youngest ever candidate.
He has stepped aside as CEO of the US-based company Nutriband to facilitate his bid.
He added that he is “confident we have at least the necessary four local authorities to consider my nomination as stipulated in Article 12.2.2 of the constitution”.
“I believe there has never been a time in our country’s history where the choice of a younger candidate being on the ballot paper has been more relevant or important than today,” Mr Sheridan said.