Labour has doubled its support over the last three months.
The latest opinion poll, due to be published tomorrow, shows the party has made significant gains, with popularity increasing from 7% to 14%.
Tánaiste Joan Burton was elected as Leader of the Labour Party at the end of June, and is now the second most popular political leader on a 45% approval rating – coming after Sinn Fein's Gerry Adams, who dropped one point to 47%.
The Taoiseach, Enda Kenny, has seen a 5% drop down to 35%, while Fianna Fáil's Michael Martin is down 6% – to 39%.
This latest Sunday Times Behaviour and Attitudes poll was conducted betweenAugust 4 – 13.
The survey was done by phone interview, speaking with 954 eligible Irish Voters, aged 18 or over, across all 43 constituencies.
When asked "If there was a General Election tomorrow, to which party or Independent candidate would you give your first preference vote?"—
• 24%said Fine Gael (- 2 points since the last poll on May 15)
• 22% selected Independents (-2)
• 19% chose Sinn Fein (-3)
• 18% said Fianna Fail (-1)
• 14% chose Labour (+7)
Green Party leader Eamon Ryan has increased his support by four points, to 37%, while his party remains unchanged on 2%.