Irish Prime Minister Leo Varadkar was preparing to resign on Thursday but stay on as interim leader, with the country's three main parties still locked in coalition talks after an inconclusive election.
The 160 MPs gathered for the first time since the February 8 vote, which saw a surge in support for left-wing republicans Sinn Fein, now the second biggest party with 37 MPs.
Fianna Fail is the largest party in the new legislature with 38 seats and Varadkar's Fine Gael has 35, but none looks likely to get the necessary support for a coalition.
The Dail -- the parliament's lower house -- is likely to adjourn at around 2000 GMT and Varadkar will offer his resignation, staying on as interim leader until a new government is formed.
In parliament, members moved to elect a speaker from a field of two candidates. Parties will later make their nominations for taoiseach (prime minister) and debate the possible candidates.
Sinn Fein, which picked up 14 seats, attracted voters by focusing on Ireland's housing shortage and health crisis. But its flagship policy on Irish unity is likely to be a top issue if it gains power.
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"I will be standing for the position of taoiseach today because I want to stand up for all of those who voted for real change and I want to deliver for all those that voted for change," said leader Mary Lou McDonald as she arrived at the Dail.
Sinn Fein is now the second-biggest party in the Irish Republic and in the largely self-governing Northern Ireland, which is part of the UK. It wants a referendum on uniting the two parts of the island within five years.
The IRA fought British rule in Northern Ireland for decades until the late 1990s, when a peace agreement largely ended violence that left more than 3,000 dead on all sides.
With none of the three main parties having the 80 seats required for a majority, at least three parties will be needed to form a government.
Fianna Fail and Fine Gael have both ruled out working with Sinn Fein, which has been forced to sound out smaller, left-leaning parties in a bid to forge broad alliance that keeps the two traditional powers out.
Varadkar told state broadcaster RTE on Monday he was prepared to go into opposition.
Fianna Fail leader Micheal Martin said Wednesday his party had formed a negotiating team "to deal with the range of crises facing the country".
Sinn Fein said it was "intensifying" negotiations with parties and independents seeking "a government for change".
As the three main parties will not work together, the Green Party -- the fourth largest with 12 seats -- may become a power broker in the next government.
It has invited all three paries to meetings from Friday to sketch out a plan for the next administration.
Talks may take some time and could result in a new election in which Sinn Fein could emerge as a favourite.
After a 2016 vote it took 70 days for a minority coalition government to form under Fine Gael, which was supported in a confidence and supply agreement by Fianna Fail.