The Green Party is set to top the European poll in Dublin, an exit poll suggested.
The increased support looks widespread, even accounting for a 4% margin of error, and could see an unexpected boost in Ireland’s two other constituencies, RTE said.
The Irish broadcaster commissioned a RedC exit poll.
The polling firm spoke to 3,230 voters in stations across Ireland.
Ireland has 13 European Parliament seats.
The main trend from the Dublin constituency is the projected poll-topping performance of the Green Party’s former junior minister Ciaran Cuffe on a suggested 23% first preference vote.
The RTE TG4 poll suggests that a candidate from Ireland’s largest party, Fine Gael’s Sean Kelly, could be re-elected, with the survey of voters in the South constituency putting him on 16% support.
Fine Gael’s Mairead McGuinness looks likely to top the poll in the Midlands/North West constituency, the research suggests.