Fianna Fail, Fine Gael and the Labour Party all ruled out accepting or seeking the support of Sinn Féin in any potential coalition arrangement after Thursday's election.
Their stance was rejected as "hypocrisy" by Sinn Féin president Gerry Adams.
Labour Party leader Pat Rabbitte said he believed Fianna Fáil would rely on the support of Sinn Féin to stay in power. Taoiseach Bertie Ahern again insisted the party would do no such deal, however.
Speaking in Dublin at the party's final press conference before Thursday's election, Mr Rabbitte ruled out any deal with Sinn Féin and said the more he saw of that party's spokespeople, the more he was convinced they had not worked out their economic policies.
"Yes they are in favour of a lot of good things, but they have no idea how they are going to pay for them," he said.
Mr Rabbitte said that if Fianna Fáil should end up relying on Sinn Féin for support, he believed there was "a definite danger that they will make do with that if it means holding on to power".
However, Mr Ahern again firmly ruled out doing any deal with the party. Speaking on the campaign trail, the Taoiseach said: "As I said a long time back, a few years ago, you can't stop anyone going into the Dáil to vote.
"But we are not going to work any arrangement. And you know, I've said this many times. If somebody goes in to vote for you one day, that would give no stability to a government. The only way a government will work is if you have an arrangement, a pact, an understanding, an agreement. And we're not going to do that with Sinn Féin."
Mr Rabbitte said: "The more I hear and see of the Sinn Féin people, their focus has been elsewhere, and once they move off the constitutional question, they don't seem to have finessed their policies at all.
They have sought to make them less outrageous during this campaign, but not because they have thought it out, or understand or have a grasp of the issues down here," he said.
Fine Gael and Labour also ruled out any pact with Sinn Féin.
Speaking at its final press briefing of the election in Dublin, Fine Gael deputy leader Richard Bruton said
Asked if the Fine Gael/Labour 'alliance for change' would refuse to accept support from Sinn Féin or ask the party not to vote for its leader as taoiseach in the Dáil, Fine Gael deputy leader Richard Bruton said: "Enda Kenny has been absolutely, categorically clear, we will not accept or seek support from Sinn Féin for...his election as taoiseach. He is absolutely clear on this - no equivocation."
Fine Gael TD Olivia Mitchell said such a situation would provide a "completely unstable government".
"It wouldn't last a week."
Sinn Féin president Gerry Adams has lashed out at the "hypocrisy" of political parties refusing to go into coalition with his party while urging similar moves in the North.
In a question and answer session on ireland.com
today, Mr Adams said there was an "irony" in Fianna Fáil celebrating the joint government in the North and "denying any role to Sinn Féin in Government in the South".
"There is a lot of hypocrisy involved with the other parties," Mr Adams said. "Most of them have played no part in the peace process."
He said voters would decide who they wanted in power and it was then up to the individual parties whether to go into government with Sinn Féin.
"The fact is, five Sinn Féin ministers from the North will be working with whoever is the next taoiseach and other government ministers in the All-Ireland Council of Ministers."
If Sinn Féin got a mandate for power it would produce "a common sense republican programme", he said. This was focused on eliminating poverty, building public services and a "programme for Irish unity".
He also accused other parties of making "blatantly dishonest promises" on taxes and on health. "The economy needs to serve the people. That means an equitable tax system to provide social safeguards and public services."