Luke "Ming" Flanagan has said he would have backed David Norris as a presidential candidate if he could have withdrawn his nomination for Sinn Féin's Martin McGuinness.
The Roscommon-South Leitrim Independent TD said he believes Senator Norris, who has now received at least 12 signatures, should be on the ballot paper.
He is calling on all Oireachtas members who have not given their support to a candidate to help facilitate Mr Norris' entry into the race.
Deputy Flanagan, who had originally backed the Senator, said he held talks with him yesterday but it was too late to transfer his nomination.
Meanwhile, Broadcaster and journalist Eamon Dunphy has hit out at critics of the Sinn Féin presidential candidate.
Fintan O'Toole of the Irish Times has said Mr McGuinness should not be President because he could be arrested for war crimes and former Justice Minister Michael McDowell has condemned Mr McGuinness for his connections with the IRA.
But Eamon Dunphy has said he will be voting for the Sinn Féin candidate.
The Mayors of Longford and Roscommon County Councils have said they will facilitate a discussion and vote to support the nominations of either Senator Norris or Dana Rosemary Scallon to contest the election.
Roscommon and Longford County Councils could hold the key to both candidates' bid to be on the ballot paper as they have not yet formally nominated any candidate.
Dana has yet to receive the formal backing of any council.