A new opinion poll conducted for The Sunday Business Post shows a slight narrowing in the gap between supporters and opponents of the EU fiscal treaty.
47% of those asked said they would vote for the treaty, while 35% said they would vote No - up two points. 18% said they had not made up their minds.
1,000 voters around the country were questioned between Monday and Wednesday for the poll, with those unlikely to vote removed from the results.
Excluding undecided voters, 58% are for and 42% against - a slight move against the treaty since the end of last month.
Support for the treaty among Fianna Fáil voters has dropped significantly, down from 72% to 52%.
The campaign does not formally get under way until Minister Phil Hogan signs the Referendum Order on Monday, however both sides are already getting their campaigns into shape.
Fine Gael and Labour urged people to vote in favour, saying the treaty would bring stability, however Sinn Féin and the United Left Alliance said it would introduce permanent austerity.
As well as opinions on the upcoming referendum, the Sunday Business Post / Red C poll also measures party support.
Fine Gael has dropped 2% since the end of March to 32%, while Labour is down one to 14%.
Sinn Féin remains in second place, up one to 19%, while Fianna Fáil has also gained one to reach 17%. Independents and others are up one to 18%.