Fianna Fail has a three percent lead over Fine Gael, according to the latest Sunday Independent/Millward Brown poll.
The poll was conducted during the Anglo Tapes controversy, when Enda Kenny said that an "axis of collusion" existed between Fianna Fail and Anglo Irish Bank.
The two parties were level on 26 percent in the last poll, but the latest survey indicates Fianna Fail is poised to win more than 50 seats in any future general election, according to the Irish Independent.
The poll shows that Fine Gael (26pc) and Labour have the support of around only one-third of the electorate, indicating the Coalition's voter support has declined by 21 percent before the government's mid-term mark.
If Fine Gael's fall continues, it could lose more than 30 seats. With the current figures Labour, at 8 percent, faces a struggle for existence as a major political party.
Paul Moran of Millward Brown, commenting on the figures, said the most worrying feature of the result for party leader Eamon Gilmore, whose satisfaction rating was at 16 pc, was the breaking of the psychological barrier where "exactly half of his own supporters are discontented with his performance."
Taoiseach Enda Kenny's crusade to abolish the Seanad is also in difficulty, with support for its abolition falling 10 percent from the last poll.
Mr Moran said of the decline that, "it seems the opening skirmishes in this debate have been lost by Mr Kenny" and that "those in favour of reform have been more sure-footed in their argument that ending the Seanad will lead to a lack of accountability."
With its close association with Kenny, defeat of the Seanad referendum would cause serious damage to the prime minister's authority.
Such a defeat is highly probable – the Taoiseach has a dissatisfaction rating of 64pc, while the Government's dissatisfaction rating is 75pc.
With only 11 pc of voters supportive of the current Fine Gael-Labour option, and the same level secured by the alternative Fianna Fail-Sinn Fein alliance, the figures would indicate that voters are increasingly open to supporting a new party.