Mr Higgins this week confirmed he will seek a second seven-year term and will offer himself as a candidate when the ministerial order for an election is made later this year.
If other candidates decide they want to contest the election, they will need the backing of either 20 members of the Oireachtas or four local authorities.
A number of Independents have signalled interest in going for the Áras: Senators Gerard Craughwell and Pádraig Ó Céidigh, Pieta House founder Joan Freeman, and artist Kevin Sharkey.
With a number seeking the Oireachtas nomination route, there are fears the votes could be spread wide and no one candidate would actually succeed in getting the required 20 signatures.
Independent TD Michael Fitzmaurice has rallied around Independent TDs and senators, urging them to unite behind one candidate but firstly declare if they will support anyone.
The Roscommon-Galway TD told the Irish Examiner last night that he now has as many as 18 Oireachtas members now willing to back a candidate. It remains unclear if there is unity behind any one figure.
Sources close to Mr Higgins have indicated he will take a step back from campaigning until the Government calls the election. This is expected to be decided by the Government in late August or early September.
Taoiseach Leo Varadkar said this week that Fine Gael would contribute funds or resources to Mr Higgins if, as expected, the party formally back him. This is the position agreed by TDs, senators, and MEPs at a meeting.
Mr Varadkar said it had to be worked out with Mr Higgins or a team on his behalf how that would work. It is expected a separate campaign team would be set up by Mr Higgins in the event of a race.
Sinn Féin will decide tomorrow if ot will back a candidate for the Áras.