Green Party leader Trevor Sargent has rejected a suggestion from the Minister for Foreign Affairs Dermot Ahern that his party could go into government with Fianna Fáil after the next election.
"I have said before that I will not lead the Greens into a coalition with Fianna Fáil in its present form. The party needs to go into opposition and radically change itself before the Greens could even consider a coalition with it," Mr Sargent told The Irish Times.
He said that a root and branch reform of Fianna Fáil and particularly its approach to ethics in public office and its relationship with vested interests would have to happen.
"Fianna Fáil would have to undergo a complete change in its culture and I don't see that happening in the short-term," said Mr Sargent.
He also pointed to Fianna Fáil's record on environmental issues. "I have to say also that the Minister has some cheek saying that his party has a good record on the environment. The European Environment Agency certainly hasn't said that, and has been very clear that Ireland is going to cost itself and every taxpayer hugely into the future."
In an interview in the Irish Examiner, Mr Ahern emphasised his own environmental credentials and added: "If you look at our record, Fianna Fáil has demonstrated that we have a good story to tell on our environmental policies and our green credentials. We introduced the plastic bag levy, plus strong initiatives on waste recycling.
"The Green Party's economic policies tend to be a bit wobbly and scary, but I could conceive them doing business with us. It's not that off-the-wall.
"Now if we were to go into a coalition, they would have to temper some of their more extreme policies that would destabilise the economic environment."
Mr Sargent accused Mr Ahern of engaging in spin politics. "It's more to do with Fianna Fáil being desperate coming into the general election."
He added: "This clearly indicates Fianna Fáil and particularly Dermot Ahern aren't really interested in our economic policies which are modelled on very successful countries and have been worked out in conjunction with business people in Ireland and are very much needed."
The Dublin North TD said the country's top 400 earners only paid 25 per cent income tax. "That is on account of Fianna Fáil making sure the tax system favours the wealthiest in this country and ensuring that the tent at the Galway races is where they pay for what they get.
"We would not stand for that and Fianna Fáil knows it. That is why they are attempting to paint this picture which is certainly not reflecting the truth."
He said Fianna Fáil would ruin the country if returned to power. "This particular Fianna Fáil is certainly not the Fianna Fáil that any party should responsibly be in government with, because it is going to be like the Titanic - it is going to be heading this country in a very dangerous direction with energy prices going up and they have not really even seen the writing on the wall."
Mr Sargent said the focus of the larger political parties was finally switching to policies on climate change and energy costs which his party had been espousing for many years. He also accused the Government of blocking progress in the wind energy industry.