Conor McGregor would not be fit to be president, the Minister for Transport has said.
Darragh O'Brien compared Mr McGregor, 37, to outgoing President Michael D Higgins, who is a former minister for arts and sociology lecturer.
"If you look at the work that Michael D Higgins has done over the last 14 years, 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," he said.
"So, I don't think he would be fit to hold that office.''
Mr O'Brien said Mr McGregor was free to challenge the process to get on the presidential ballot paper but that the Constitution was "clear".
He was responding to comments from Mr McGregor to The Sunday Times where he said he is considering a legal challenge to the eligibility rules for the presidential elections.
To become a candidate, a person must be nominated by either 20 members of the Oireachtas or four local councils. They also must be an Irish citizen who is 35 or older.
An election is expected towards the end of October, as it must take place in the 60 days before outgoing President Michael D Higgins' term ends on 11 November.
So far, two candidates have secured sufficient nominations to get on the ballot: former farming journalist and EU commissioner Mairead McGuinness, who is the Fine Gael nominee; and Catherine Connolly, an Independent TD and former Galway mayor who has received the backing of opposition parties and independents.
Several figures have said they intend to seek the nominations needed to get on the ballot, including Riverdance star Michael Flatley and previous presidential candidate Peter Casey, as well as Mr McGregor.
Businessman Gareth Sheridan also declared his interest in the Áras race today.
The former CEO of Nutriband said he in confident of securing the nomination through at least four local authorities.
Mr Sheridan, who turns 36 in two weeks, said he is hoping to be the youngest ever candidate for the office of Presidency.
Speaking at the Tullamore Show where he confirmed his intentions, Mr Sheridan said he believes there has never been a time in the country's history where the choice of a younger candidate being on the ballot paper has been more relevant or important.
Asked about Mr McGregor's intention to legally challenge process to be nominated as a presidential candidate, Minister O'Brien said he was within his right to take a case but did not believe he would be nominated.
'Constitution is clear'
"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," the Fianna Fáil TD said.
"I don't envisage he'll be nominated to run for president. But look, I think it's open to any citizen to take a challenge, should they wish.
Last month, Mr McGregor lost his appeal against a civil jury's finding in favour of Dublin woman Nikita Hand, who accused him of rape.
Ms Hand, 35, successfully sued McGregor in a civil court over an incident in which he was alleged to have "brutally raped and battered" her in a penthouse at a south Dublin hotel in December 2018.
Ms Hand was awarded almost €250,000 in damages and Mr McGregor was also ordered to pay about €1.3 million in legal costs following the November trial.
Additional reporting: Dimitri O'Donnell and Sinéad Hussey
