With all the main parties finalising their plans for the contest in just over a year's time, Ahern has chosen to stress his links with the trade unions in a direct challenge to Rabbitte's decision to rule out any post-election deal with Fianna Fail.

"Sure Pat doesn't believe it himself, " the Taoiseach says in an exclusive interview in today's Sunday Tribune. "They know trade unionists vote for us. If it falls that way, Pat Rabbitte will listen to his trade union membership."

The strident tone of Ahern's remarks about the Fine Gael-Labour alternative clearly signals that the next election will be more politically charged than recent contests. In a scathing attack on the main opposition parties, Ahern claimed the alternative lacked coherent policies.

This message is set to become a Fianna Fail theme in the months ahead, as is the Taoiseach's warning that Ireland's economic success would be threatened by a return to power of parties who when "they had the chance at running the economy showed gross incompetence".

"I don't see coherence any day on issues from the opposition, " said the Taoiseach.

"Look at this week . . . Pat Rabbitte was going ga-ga over the Great Southern Hotels while Fianna Fail was issuing a statement welcoming the sale. We haven't seen one substantial document yet that's jointly theirs and jointly costed. They have one policy, to replace the current government."

With Fine Gael and Labour about to publish a joint-position paper on waste in public spending, Ahern claimed their decision to focus on expenditure over-runs was copied from advisers to the British Conservative party.

He said the current government would "vociferously fight" its record on spending, despite opposition claims of waste and mismanagement.

"It's easy to sit back on the sidelines and say, 'Oh there's a cheaper way'."

In today's interview, the Taoiseach also accuses Enda Kenny and Pat Rabbitte of being irresponsible in their comments on immigration.

He questioned recent opposition claims that lower-paid migrant workers were taking jobs from Irish employees.

Research for all the main parties is showing that immigration has emerged as a real voter concern alongside traditional areas such as health, transport and childcare. "It's an issue because a high proportion of the people in this country now are non-Irish.

We've come from figures where immigration was little or nothing, and now it's quite a fear. So how that is handled into the future is hugely important, " Ahern said.

The Taoiseach again firmly ruled out sharing power with Sinn Fein, and said a continuation of the current coalition with the Progressive Democrats was his favoured option. But if it failed to get a working majority in the Dail he would look at the possibility of a coalition with Labour, irrespective of the anti-Fianna Fail stance being pursued by that party's current leader.