Taoiseach Enda Kenny has blamed Fianna Fail supporters returning to the fold for his party's slump in the polls.
He said the result in the previous elections in 2011 was extraordinary. It followed the collapse of the Celtic Tiger and unhappiness over how his rivals handled the financial crash.
The re-elected Mayo TD pledged to stay at the helm to help steer the country to stability as the outcome of the election remained mired in uncertainty.
"Democracy is always exciting but it is merciless when it clicks in."
He refused to step aside and would not say how he planned to form a government.
"I have a duty and a responsibility to work with the decision that the people have made to provide the country with a stable government - that I intend to do fully and completely."
Mr Kenny was mobbed by Fine Gael supporters as he arrived with his wife Fionnuala at the Royal Theatre in Castlebar this evening for his re-election as TD for Mayo - returned with 13,318 votes.
But, nationwide, the party's share of the vote dropped back to levels of a decade ago.
Mr Kenny added: "Quite a lot of people who might have supported the Fianna Fail party who were ashamed to vote in 2011 came back out to vote yesterday.
"Clearly the 2011 result was extraordinary in getting 76 seats."
Over the years Fine Gael has normally averaged in and around 50.
Mr Kenny said: "This is a disappointing day for our party and it is particularly disappointing for those who are candidates and who have lost their seat."
He said he would meet ministers to discuss the results soon.
Mr Kenny arrived before 9pm at the theatre. He was greeted by a scrum of cameras and the applause of the party faithful.
Police pushed a passage through the crowds in front of him as he shook hands and greeted familiar faces.
John McHugh, 68 and from Castlebar, was tallying votes. A withered Kenny sticker which had seen many doorsteps was peeling from his jacket as he mused on coalition with Fianna Fail.
"I think the biggest problem Fianna Fail would have is that if they change the rules is it has to be agreed upon by the wider party - which would be more problematic.
"I think politicians are pragmatic, their supporters are not."
A Fianna Fail canvasser confirmed the fear. "I will never vote again if they do."