Sinn Féin leader Mary Lou McDonald has said "the gamechanger proved to be a gamechanger", regarding the party's decision to back Catherine Connolly in the Presidential Election.
Ms Connolly received just over 63% of first preference votes and was elected on the first count.
Her opponent in the race, Fine Gael's Heather Humphreys, secured just over 29%.
Speaking on RTÉ’s The Week in Politics, Ms McDonald said that Ms Connolly secured a "historic" and "unprecedented" mandate.
She said Ms Connolly’s election showed the public that it was possible to win an election beyond Fianna Fáil and Fine Gael.
"When we come together, when we work collaboratively, when we show up for each other, we can win," she said.
Ms McDonald said the victory was especially important for young people in Ireland.
"I have always believed that this election offered the opportunity to have somebody in the corner of that generation. The Government isn't, their Uachtarán is," she said.
The Sinn Féin leader said Ms Connolly is a person of "immense qualities", including "grace, compassion and also steel".
"And I think she will be that inclusive, progressive, kind compassionate voice."
She said the presidency is an incredibly important role and there was a lot at stake in this election.
"Uachtarán na hÉireann is the voice of the Irish people, it is the person who speaks to us, it is the person who speaks for us."
The Galway West TD's victory in the election will trigger a by-election in the constituency to fill her seat, which must be held within six months of her inauguration as the tenth President of Ireland.
Mary Lou McDonald said Sinn Féin will contest the by-election, adding that the left parties who supported Ms Connolly are individual distinct parties.
She said she hoped that the parties will transfer between each other.
President Higgins congratulates president-elect Connolly
President Michael D Higgins congratulated president-elect Connolly on her election victory, while several senior politicians said a response is needed to the 213,738 spoiled votes.
Following her election victory, President Higgins said Ms Connolly will have the full support of his office as she prepares for her inauguration on 11 November.
In a statement, President Higgins said: "I have this evening spoken by telephone with the president-elect, Catherine Connolly. I congratulated the president-elect on her election as the tenth President of Ireland on what is a momentous day for her and her family.
"The president-elect will have the full support of this office as she prepares for her Inauguration next month."
Taoiseach Micheál Martin said he looked forward "to working with the new president", while Tánaiste Simon Harris said "today is her day" in relation to Ms Connolly.
Members of the political parties who backed Ms Connolly's campaign, including the Green Party, Labour, People Before Profit-Solidarity, Sinn Féin, and the Social Democrats, also congratulated the Galway West TD.
'Voice for peace'
In her victory speech last night, the president-elect vowed to be an "inclusive" president for all.
Speaking at Dublin Castle, she said: "I will be a voice for peace, a voice that builds on our policy of neutrality, a voice that articulates the existential threat posed by climate change, and a voice that recognises the tremendous work being done the length and breadth of the country.
"Our whole mantra during this campaign was that we can shape a new Republic together and we can use our voices for those who haven't the ability, or for whom the circumstances don't allow it."
