Ivana Bacik has won the Dublin Bay South by-election.
Ms Bacik was deemed elected without reaching the quota.
An elated Ms Bacik arrived at the Simmonscourt count centre to a huge roar signalling she will be the newest TD for Dublin Bay South.
"I'm just so deeply honoured and so grateful to have received such a such an overwhelming support from across my home constituency here in Dublin Bay South," she said.
"I'm absolutely over the moon," she added, paying tribute to all those worked so hard with her over the last few weeks, along with activists from the Repeal and Marriage Equality referendum campaigns.
She said the party had emphasised its core messages on the need for change on Housing, childcare and elder care, on community amenities and on climate justice, along with "Labour values" of equality and solidarity.
"I'm just so grateful that message has been heard and also that so many people have shown the need to ensure a balanced representation in the constituency -- to have a strong progressive woman's voice."
She said it had been "a crowded field and a very intense campaign," the first run under Covid conditions.
with public health restrictions, and with a huge focus on it because it was, it is just a by election. "I do just want to pay huge tribute to all of the other candidates. We ran I think a respectful and courteous campaign and I think anyone who runs for election deserves to be treated with respect.
She paid tribute to her mom, Rita, her partner Alan and two daughters, who all attended.
Asked what message her big win sent to the Government parties, she said it was "loud and clear throughout the campaign the need for change that people wanted to see."
Count details can be seen below, with Ms Bacik taking a significant lead over Fine Gael’s James Geoghegan, with counting ongoing.
Indications from the tallies earlier in the day showed that Ms Bacik polled well across the constituency and will beat Mr Geoghegan, who had been hoping to retain the seat vacated by former housing minister Eoghan Murphy in April.
While the result is set to be a blow to Tánaiste Leo Varadkar and Fine Gael, the tallies for Fianna Fáil candidate Deirdre Conroy would indicate the Fianna Fáil party has performed extremely poorly and will struggle to outpoll Independent Mannix Flynn.
A senior Fianna Fáil source said it was a “very disappointing” result for Taoiseach Micheál Martin’s party.
While a senior Fine Gael source also the result is a blow for the party, given that the party “threw the kitchen sink” at the by election.
The source said: “It’s a big disappointment.
“Most people, even our opponents would agree, we tried everything.
“What’s happened is that people who didn’t want Fine Gael consolidated around Ivana.
“What would be beginning to worry some people in the general trend. Losing a general election, losing a by election - there’s hasn’t been a by election won under Leo.
“What does it say about the trend or the future for Fine Gael?”
Labour leader Alan Kelly said that he is “very proud” of Senator Bacik’s performance and the campaign that was run.
He said that this is a “signal” to the Government as to what “the people of Ireland are thinking”.
“We have demonstrated today that there are progressive alternatives and the Labour Party has been the progressive alternative, always been the left-wing party that people can look towards,” he told reporters at the RDS.
He said that the party has had “a very difficult 10 years electorally” and that this is an “important moment” for Labour.
“We can replicate hopefully what we can do here in all the different constituencies around the country,” he said.
The 100pc tally is showing that Senator Ivana Bacik has 30.17pc of first preference votes.
FG's James Geoghegan is at 26.2pc of first preference votes and Sinn Féin's Lynn Boylan is at 15.8pc.
Green Party's Claire Byrne is at 7.9pc and Fianna Fáil's Deirdre Conroy at 4.8pc.
Independent DCC Cllr Mannix Flynn is at 3.2pc and Social Democrat Sarah Durcan is at 3.1pc.
Independent candidate Dolores Cahill was refused entry into the count centre as she refused to wear a mask.
She remains outside the count centre and tallies show she is at 0.6pc of first preference votes.
The count centre is much less busy than usual times due to strict numbers allowed inside to facilitate social distancing.
Each party is only allowed a small set number of people and tallymen and women are being shared across parties.
Turnout in the contest picked up on yesterday evening after a relatively slow start.
By around 9pm, the average voter turnout had reached 40pc, compared to 34pc at 8pm and 24pc in the early evening, according to figures from RTE.
That is on par with the last by-elections in 2019, when four contests saw a turnout of between 25 and 35pc.
But it remains well below the 2020 general election, when turnout was 62.9pc nationally, and 52pc in Dublin Bay South.
It is the first electoral contest since the pandemic began, but it remains to be seen if that impacted voter turnout.
A series of safety arrangements were put in place, to ensure the by-election was held in accordance with Covid-19 public health advice.
Hand sanitiser was available at all polling stations, while voters were asked to wear masks and observe social distancing rules when inside.
Polling hours were extended by 30 minutes to assist Covid-19 arrangements, closing at 10.30pm instead of the traditional 10pm.
Other candidates include Deirdre Conroy of Fianna Fail, and Councillor Claire Byrne running for the Green Party.
The Social Democrats have chosen Sarah Durcan, while the People Before Profit candidate is Brigid Purcell.
The current TDs in the constituency are Fianna Fail’s Jim O’Callaghan, Sinn Fein’s Chris Andrews and Green party leader Eamon Ryan.
Long considered a Fine Gael heartland, Dublin Bay South is home to the affluent suburbs.
The other candidates in Dublin Bay South are Justin Barrett (National Party), Jacqui Gilbourne (Renua), Mairead Toibin (Aontu) and independents Dolores Cahill, Peter Dooley, Mannix Flynn, John Keigher and Colm O’Keefe.