The Irish on Thursday will vote on Thursday on whether or not to ratify the new European Union Fiscal Treaty.
Ireland is the only country among the treaty's 25 signatories that requires a national vote.
Opinion polls suggest a majority will vote 'Yes' - though many where expected to decide at the last minute.
The treaty allows EU members to co-ordinate their budget policies and impose penalties on rule-breakers.
Signed in February, it commits all ratifying members to achieve budget deficits of less than 0.5% of economic output. Last year, Ireland's deficit reached 13.1%.
Irish voters have twice rejected European Union treaties - in referendums in 2001 and 2008 - though both votes were then overturned in subsequent polls.
Because of the treaty's complexity, a high turnout is not expected.
Those against the treaty argue that austerity is not working and suggest that the country should instead default on debts at five nationalised banks.
In a nationwide television address before campaigning ended, Prime Minister Enda Kenny urged people to vote in favour of the treaty, the BBC reports.
I ask you to make a further contribution by coming out to vote 'yes' on Thursday. Yes to stability. Yes to investment. Yes to recovery. Yes to a working Ireland, he said.
Sinn Fein president Gerry Adams, who is campaigning against the treaty, told voters not to be fooled.
Be wise. Join with the millions across Europe who are demanding an end to austerity. On Thursday, vote no,'' he said.
Results are not expected until late on Friday.