Fianna Fáil leader Micheal Martin has denied Sean Gallagher is a "proxy candidate" for the party, claiming the the label is "ridiculous" despite ongoing support from grassroots members for his Aras bid.
The opposition leader was forced to reject the claim on Tuesday after Mr Gallagher quickly won the support of four councils needed to officially enter the presidential race on Monday - in part due to the widespread backing of Fianna Fáil councillors.
Speaking at the start of Fianna Fáil's two day pre-Dáil think in at the Grand Hotel in Malahide, north Dublin, Mr Martin said TDs and senators "took a decision" earlier this year to back Michael D Higgins' re-election bid.
Despite party TD Eamon O Cuiv's rumoured interest in entering the race and ongoing private calls from party members to run a candidate, Mr Martin said nothing has changed in this regard.
And asked directly about Mr Gallagher, he denied the businessman with close ties to the party is effectively Fianna Fáil's "proxy" presidential candidate.
"I think that is ridiculous. Clearly not," Mr Martin insisted.
"First of all the Fianna Fáil party took a decision and informed a decision to support the candidature of of the outgoing president Michael D Higgins as we believe he has performed very well on behalf of the country and with distinction abroad and here as well in our own country.
"He is very well placed given his personal background, his political background, his depth, his intellectual capacity to take us through, as president, what will be a very important series of events with the commemorations of the war of independence, the civil war and beyond that.
"I welcome other candidates coming into the race. I made it very clear that councillors have an entitlement to facilitate the nomination of other candidates and we are not in the business of blocking candidates.
"Sean Gallagher, along with others, have decided to enter the race, and has secured nominations and we look forward to the campaign as it ensues," he said.
As of Tuesday afternoon, Mr Gallagher and Independent senator Joan Freeman are the only two presidential candidates to have successfully been nominated to officially enter the race alongside Michael D Higgins.
However, it is widely expected fellow businessman Gavin Duffy and potentially one other candidate will also succeed in receiving enough support in the coming fortnight to contest next month's presidential election.