The United Nations will decide later whether to give Ireland a seat on the Security Council after a two-year charm offensive by Irish diplomats.
Ireland is up against Canada and Norway for two of the five temporary seats that are open, and needs to win a two thirds majority.
Voting is expected to begin about half past two this afternoon, and the first round of results won't be known until eight o'clock tonight.
Minister for Foreign Affairs, Tánaiste Simon Coveney, says the Irish diplomatic corps has been building up to this for four years.
"This is arguably the biggest day for Irish foreign policy in 20 years.
"There are only 10 non permanent member states on the security council at any given time, so I've probably been speaking directly to the foreign ministers or prime ministers of 100 countries over the last two years in terms of drumming up support for Ireland.
"I think we're doing well, but we won't find out until 8pm this evening whether it's well enough."
