The republican party first toasted massive success in Dublin with Lynn Boylan taking a Brussels seat last night before building on that victory with winners expected in the South and Midlands-North West.
And in Northern Ireland Martina Anderson is favourite to top the poll ensuring European representation for the party in all parts of the island.
On the back of a resounding return in the local elections for Sinn Fein - three times as many council seats as previously held - the results mark a dramatic shift in the political landscape and a move from traditional parties to the left-wing, anti-austerity candidates and independents.
One of the few politicians to maintain their massive personal vote was in the South where outgoing MEP Fianna Fail’s Brian Crowley topped the poll with a landslide 180,829 votes.
Liadh Ni Riada of Sinn Fein is in the running to take a seat in that constituency after polling 125,309 votes.
Party president Gerry Adams rejected claims from Taoiseach Enda Kenny that the unprecedented swing to left-wing candidates was borne out of frustration and nothing more than a protest.
“This is deep rooted, it’s profound, it’s a sea change. The landscape here politically has changed,” he said.
The party’s candidate, Matt Carthy, is also in the fight for a seat in the Midlands-North West where Luke Ming Flanagan, an anti-establishment, pro-cannabis, eurosceptic independent, was on course to top the poll.
He said his support was a direct reflection of public opposition to spin from government despite four years of austerity.
“The message that the Govenment have been continually putting out is an insulting message - everything is all right, the green shoots are coming up,” Mr Flanagan said.
Labour suffered the bitterest defeats over the weekend with leader Eamon Gilmore under deepening pressure.
Questions over his leadership and the need for a revived programme for government and cabinet reshuffle have been fired from the backbenches.
Talks are planned between Foreign Affairs Minister Mr Gilmore and Mr Kenny and separately also among Labour ministers.
Sinn Fein’s success comes despite the massive controversy over the arrest of party president Gerry Adams during the election campaign.
“The Government dismisses this as a protest vote or, as the Taoiseach claims, a sign of frustration by the electorate. This is wrong,” Mr Adams said.
“The Government has been sent a very clear message. They do not have public support for the damaging policies they are implementing.
“The voters have called time on this government. They should change political direction or call a general election.”
Most of Ireland’s 11 MEP seats remain to be filled with counting continuing in the Midlands-North West and in the South.
But counting at the RDS in Dublin resumes this lunchtime where a recount has been ordered after Green Party leader Eamon Ryan, a minister in the previous government, sought to close a gap of about 1,200 votes to take the final seat.
The seats in the capital should be finalised tonight.
But it is the junior coalition partners Labour who are clearly bearing the brunt of the backlash for years of punishing cutbacks, with candidates losing seats nationwide.
High-profile casualties in the Labour drubbing include Lord Mayor of Dublin Oisin Quinn and Lord Mayor of Cork Catherine Clancy, who failed to keep their council seats.
There was one rare victory for the coalition with Fine Gael retaining its seat in a by-election in Longford-Westmeath, where Gabrielle McFadden takes over from her sister Nicky who died from motor neurone disease last March.
In the other by-election, a former Labour seat in Dublin West was won by the Socialist Party’s Ruth Coppinger.