President Michael D Higgins has confirmed that he will seek a second term in office.
In a statement, Mr Higgins said he will be "offering himself as an independent candidate".
Prior to the contest in 2011, he promised to only be a one-term president, with the announcement ending months of speculation over his intentions.
Yesterday, Sean Gallagher, who failed in his presidential run seven years ago, opened the door to contesting this time around as well.
Mr Gallagher did not announce his intention to run, but wrote a letter to the Mayor and Cathoirleach of every local authority asking that they formally schedule time to hear from potential presidential nominees in the coming weeks.
Sources suggest Mr Higgins would have liked to be returned as President without an election - but that now seems unlikely.
Reacting to the news, Sinn Fein leader Mary Lou McDonald said: "I actually think we need an election at this time."
Labour leader Brendan Howlin has said the party is "delighted" that Mr Higgins has confirmed he will seek a second term.
He said he has been an "exemplary President" who has been a source of pride for many.
Mr Howlin said he expects the Labour Party's executive board to vote to campaign for Mr Higgins.
Asked about the timing of the announcement, just days ahead of the Dail recess, Mr Howlin said any potential candidate could have begun their campaign at any stage over the past seven years.
People Before Profit TD Brid Smith said she would like to see him run unopposed, without the need for a presidential election later this year.
"I would be happy to support Michael D Higgins and I think most people believe, in so far as a figurehead exists and does so much for the country, that he has done a reasonably good job," she said.
"He is quite a bold and a brave individual. He is somebody that by and large is on the right side of history and I would be happy to support his presidency.
"I wouldn't be interested in seeing an election. If he is prepared to go forward then I think we should endorse him and say 'go for it'. If an election happens, an election happens - but I would be happy for him go forward unopposed."
A vote would take place in October. Fianna Fail and the Labour Party have already backed Mr Higgins and Fine Gael is almost certain to do likewise in the coming days.
The Government has been informed of his decision.
Mr Higgins said his "programme of official duties and engagements continues".
Among those who may run against him are Independent senator Gerard Craughwell.
Mr Craughwell has been critical of Mr Higgins reneging on his promise to be a single-term president.
Joan Freeman, the founder of Pieta House, is the latest name to be added to the mix of independent candidates who are working behind the scenes to secure nominations.