Sean Kelly and Heather Humphreys look set to battle it out to be Fine Gael's candidate for the country's next President.
They will seek the party's approval after it opened a two week nomination process.
Speaking on the Joe Finnegan Show on Northern Sound, Ms Humphreys said she has "decided to go for it", having originally ruled herself out of the race three months ago.
It follows the shock announcement by Mairéad McGuinness last week that she would now not run for Fine Gael due to health reasons.
Ronan Gargan reports.