Sinn Féin has launched its Stormont Assembly election campaign, describing the 5 May poll as the "most important in a generation".
The result could see the party become the largest in Northern Ireland for the first time, and in line to take the post of First Minister.
The party had 27 candidates elected in 2017, just one fewer than the DUP.
Sinn Féin is fielding 34 candidates, just over half of them women, across the 18 constituencies.
A series of recent opinion polls suggest it has a chance to become the largest party this time around.
Several hundred Sinn Féin members packed into the ballroom of the Europa Hotel in Belfast city centre for the launch event.
"The facts are that the balance of power at Stormont has shifted irreversibly and political unionism must come to terms with the fact the world is moving on fast," the party's leader in Northern Ireland Michelle O’Neill told them.
"Sinn Féin will be defending, not renegotiating the Good Friday Agreement now, or in the time ahead.
"We will not be shifting any goalposts to satisfy unionism before, or after elections."
She strongly criticised DUP leader Jeffrey Donaldson, describing his decision to collapse the Stormont Executive by removing Paul Givan as First Minister as "political vandalism".
He has also refused to be drawn on whether his party will go back into power-sharing if Sinn Féin is the largest party and is entitled to the First Minister post.
"This is heard by those of us within nationalism as unionism doing democracy on only unionism's terms," she said.
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This is about much more than Stormont for Sinn Féin.
A good result, topping the poll, would boost its drive to become the largest party across the island and to lead governments on both sides of the border. A poor result would seriously dent those ambitions.
The significance was signposted at the end of Michelle O’Neill’s speech.
"On fifth May, this election has the potential to bring about an historic and seismic shift in the political landscape," she said.
"Huge change is on the horizon."
The event was also addressed by Sinn Féin president Mary Lou McDonald, who said the success of the next Stormont administration would be based on delivery.
"We don't have to agree on everything, but we must agree that we are committed to the Assembly and the Executive," she said.
"We must agree that we will deliver for the people who elect us. We must agree that we are willing to roll up our sleeves and get on with the business of government."
The party leaders were highly critical of the British government on a day when a long running dispute over the Irish language resurfaced.
Northern Secretary Brandon Lewis has failed to deliver on a promise to Sinn Féin to introduce an Irish language act in Northern Ireland if Stormont did not agree to do so by last October.
He has now confirmed that there will not be any movement before the election, a move Sinn Féin has described as a clear breach of faith.
Ms Lou McDonald’s criticism included a reference to her fellow Trinity College graduate Edward Carson, regarded as the founding father of Ulster Unionism after he felt betrayed by the Conservative government in 1921.
Both of them, she said, shared "a healthy scepticism of Tory governments, born of lengthy experience."
