Irish general election: What's at stake for the parties?
While there have been referendums in the past on a Saturday a general election is most unusual.
Taoiseach (Irish prime minister) Leo Varadkar had, in the past, said he wanted a late Spring or early Summer election but, after recent by-election defeats, his position in the Dáil (Irish Parliament) became untenable.
The House was due to sit again on Wednesday afternoon after its Christmas break but that will not now happen.
The newly elected TDs will now gather on 20 February for the 33rd Dáil.
Even as the cabinet was meeting on Tuesday morning and Mr Varadkar was briefing his Fine Gael party colleagues and other independent ministers on the decision to dissolve the current Dáil, election posters in his Dublin West constituency were going up.
Opinion polls have put his party marginally ahead of Fianna Fáil, the main opposition party led by Micheál Martin.
But last week's local election results - normally a good indicator for what will happen in a general election - suggested that Fianna Fáil has a very good result and has made headway in Dublin.
The Irish capital has, for nearly a decade, been a relative black spot for the main opposition party.
Sinn Féin, led by Mary Lou McDonald, goes into this election knowing it will do well to hold onto its current number of seats.
The party has had a series of poor results recently notwithstanding one by-election win and both the main parties have ruled out going into coalition with Sinn Féin.
Fine Gael, which has been in power for nine years, is likely to concentrate on a healthy economy.
It will also point to Fianna Fáil's stewardship that led to the Celtic Tiger's crash and the EU-IMF bank-related bailout a decade ago.
The opposition parties will concentrate their fire on the government's record on health and housing, including homelessness.
The UK will leave the EU during the course of the campaign on 31 January and Fine Gael hopes it will get a boost from voters being reminded by what they see as its sure-footed handling of the issue.
But the opposition parties will point to the Dáil consensus on the issue.
This will be Leo Varadkar's first election campaign as taoiseach and he will be up against a proven campaigner in Micheál Martin.
At this early stage, a very close result is expected but politicians from all parties know campaigns develop their own momentum.