The Sinn Féin leader has said it is time for a new government, describing the rotating governance by Fianna Fáil and Fine Gael as "political hokey pokey".
Mary Lou McDonald hit out at what she said was the "cosy club" of parties that have been in government for a century.
She used her keynote speech at the party's Ard Fheis in Dublin to say that young people have been badly let down, particularly by a failed housing system.
Ms McDonald's speech was met with a standing ovation by more than 2,000 Sinn Féin members who gathered in the RDS in Dublin.
She also condemned Vladimir Putin's war in Ukraine, sent condolences to the families of those who died in the Creeslough tragedy and criticised the treatment of the Traveller and LGBTQ communities.
Ms McDonald said that the two main parties in Government have "had their time" and their chance, saying it is a time for a new government.
"A government of change. A government for the people," Ms McDonald added.
"Change can't be stopped by Fianna Fáil and Fine Gael, now so joined at the hip that it doesn't matter to them which leader is Taoiseach.
"So long as it's one of them. Leo leaves, Micheál goes in. Micheál leaves next month, Leo goes back in. In. Out. In. Out. Political hokey pokey.
"That's the cosy club that has run this State for a century.
"Fianna Fáil and Fine Gael have had their time, had their chance. It's time for a new government. A government of change. A government for the people," she said.
"Change can't be stopped by the chaotic Tories in London either.
"They can't run their own country without bringing it to the brink of financial ruin. They certainly have no right to tell the people of Ireland how to run ours," she said.
'No turning back'
Referring to Sinn Féin's historic win in May in the Northern Ireland Assembly election, which resulted in the party winning the most seats for the first time, Ms McDonald said there is "no turning back".
She told members that the result of the election reflects the "spirit for change".
"For the first time, a republican, a nationalist, a woman from Tyrone, was elected as First Minister in a state designed to ensure that this could never happen," Ms McDonald added.
"Well friends, it did. Michelle O'Neill a first minister for all. There is no turning back.
"There is now no job in the land off limits to anyone. The days of second-class citizenship are over," said Ms McDonald.
The Sinn Féin leader said change means "taking those final steps to full nationhood, ending partition, reunifying Ireland".
In a message to those who she said were "apprehensive" about Irish unity, Ms McDonald said that all will be "cherished, included, respected as equal citizens".
She called on the Government to "immediately establish a Citizens' Assembly on unity".
"If this Government refuses to hear tomorrow coming, if it does not establish a Citizens' Assembly, Sinn Féin in government will."
Earlier today the Sinn Féin leader called on the British government to set out a clear plan for "good faith" negotiations with the European Union on the Northern Ireland Protocol.
Speaking at the opening of her party's ard fheis, she said the outcome of last May's elections should be respected and there should be a functioning Executive in Northern Ireland.
"In the event that we are plunged back into another period of stalemate of course there will have to be an election... is that where I want to be? Absolutely not, because we want government."
She urged the British government to make a clear statement as to what happens next and to set out how an agreement can be concluded with the EU on the Northern Ireland Protocol.
First Minister-designate Michelle O'Neill accused the Democratic Unionist Party (DUP) of punishing the public.
She said it was "no secret" that the DUP did not want to serve as a deputy first minister to a Sinn Féin first minister.
"People know that is the real reason behind the DUP's blockage," Ms O'Neill said.
Discussions on housing, a united Ireland and the cost-of-living crisis will all feature on the agenda of the Sinn Féin Ard Fheis, which is taking place at the RDS in Dublin.
It is Sinn Féin's first full in-person gathering since 2019, with Covid-19 restricting attendance numbers at previous conferences.
The ard fheis comes at a time when the main opposition party ranks high in the polls and harbours hopes of leading the next government.
Separately, Ms McDonald defended her decision not to cooperate with journalist Shane Ross's recent biography of her.
She said his decision to write a book about her was akin to her deciding to write a book about the Taoiseach.
She said she has a mortgage on her home, which is still being paid, adding that she is lucky to have a family home.
On another issue, Ms McDonald described Eoin Ó Broin's call for the Chief Economist at the Department of Finance to be sacked as "wrong" saying that people in the public service have a job to do.
Mr Ó Broin has since apologised for those remarks.
The Sinn Féin leader also addressed the "criminal activity" of former Sinn Féin councillor Jonathan Dowdall saying she was "profoundly shocked" to learn about this.
If this had been known, he would not have got "anywhere near" Sinn Féin, she said.
Additional reporting Micheál Lehane and Tommy Meskill