Support for Fine Gael has fallen to 19%, the latest Sunday Independent/Ireland Thinks opinion poll suggests.
Sinn Féin has also seen a fall in support, according to the poll, down one point to 31%.
However, it remains the most popular party.
The poll suggests that support for Fine Gael is now on par with Fianna Fáil.
Micheál Martin's party has held steady when compared with last month's poll at 19%.
Support for the Social Democrats is also unchanged, with the party receiving 6% support amongst those polled.
Solidarity/People-Before-Profit has seen an increase of two points to 4%.
The Green Party and Aontú are both on 3%, unchanged from last time.
Independents and others are up one point to 13% while the Labour Party has seen a drop of one point to 2%.
The Sunday Independent/Ireland Thinks poll was conducted today and yesterday.
It surveyed 1,076 people and has a margin of error of +/- 3%.
