The Government has been accused of holding a gun to voters' heads to force them into a Yes vote in the referendum.
Finance Minister Michael Noonan issued a stark warning that refusing to accept the European stability treaty would result in a much tougher budget next year - claims opposition TDs have described as scaremongering.
Sinn Fein deputy leader Mary Lou McDonald said the Fine Gael-Labour coalition had been guilty of bullying the electorate.
"The Government has no positive argument why the people should support this treaty, but they have resorted to threats and bullying," said Ms McDonald.
She added that the pro-treaty campaign is based on "sheer dishonesty", which will result in years of austerity and plunge Ireland into another economic crisis.
Taoiseach Enda Kenny vehemently rejected the scaremongering accusations.
He also leapt to Mr Noonan's defence, saying he was merely pointing out that Ireland is in a Programme for Government and that tough budgets lie ahead.
"It's not a question of attempting to scare anybody," said Mr Kenny.
"It's an attempt to deal with what we know is a reality."
He said Fine Gael will not involve itself in scare tactics.
Mr Kenny launched his party's campaign for a Yes vote in the referendum which, if successful, will see Ireland ratify the treaty to bring about stricter budgetary rules.
He has argued it will also ensure the country has access to emergency funds should it ever need another bailout.
The Socialist Party kicked off its campaign against the treaty today also.
TD Joe Higgins said Mr Noonan's remarks were evidence that while the Government initially adopted a "nicely, nicely" approach to the public, it has quickly resorted to holding a gun to their heads.
Earlier, Mr Noonan suggested Ireland is staring down the barrel of another slash-and-burn budget if the European fiscal treaty is rejected.
He warned a No vote on May 31 would force him to draft a much tougher budget.
"If there is a No vote, the budget I'm planning for later this year will be dramatically more difficult," Mr Noonan said.
But Socialist Party TD Clare Daly pointed out that the effects of the treaty would not kick in until Ireland came out of its current bailout programme in two years.
She said any tough budgetary decisions made this December would be because of Fine Gael and Labour - not a rejection of the treaty.
The Referendum Commission will launch its public information campaign on Thursday, which will include TV adverts and leaflets outlining the facts of the treaty - in a completely impartial way.
The vote will take place between 7am and 10pm on May 31.
The count will take place in centres across the country on June 1.