The Labour nomination will be decided by TDs, senators and a small number of party officials on June 19.
Michael D Higgins: The Labour stalwart has long desired a shot at the presidency, but there is a growing body of opinion in the party that his time may have passed.
Fergus Finlay: The Barnardos chief and former party adviser is Mr Higgins's strongest competitor for the party nomination and he is winning over younger members of the increased Labour parliamentary party.
Kathleen O'Meara: The former Labour senator is also looking for the party's nomination but only declared in recent weeks.
FG will decide its candidate over the summer.
Mairead McGuinness: The Leinster MEP declared her hand a few weeks ago, but the former journalist, who has been away from domestic politics since failing to win a seat in the 2007 general election, might lose out because of a lack of heavyweight political experience.
John Bruton: Former Taoiseach John Bruton has been coy about his intentions, but there is a feeling the FG nomination is his if he wants it.
Sean Kelly: Ex-GAA president and current Munster MEP Sean Kelly has also been mooted as a candidate, but it would be a challenge for him to beat Mr Bruton and Ms McGuinness.
MEP Brian Crowley has been consistently mentioned as a candidate, but there is serious doubt whether Fianna Fail will run someone at all.
David Norris: Already has the backing of one county council and should have a sizeable chunk of independent TDs and senators in the Oireachtas. To get in the race proper, a candidate needs the support of four councils or 20 Oireachtas members. Almost certain to get a nomination, and will be a serious contender for the Aras.
Mary Davis: Long associated with Fianna Fail, she yesterday announced she will run as an independent, and, interestingly, insisted she will focus on the council route rather than look for a nomination from Oireachtas members.
Sean Gallagher: Another candidate associated with Fianna Fail, but running as an independent, the 'Dragon's Den' star is also canvassing councils but is seen as an outside bet.
Dana Rosemary Scallon: Ran in the 1997 presidential election and dropped out of running in 2004 when it was clear Mary McAleese would not be beaten. Has not ruled out running again.