Arlene Foster and Michelle O'Neill have publicly clashed over Sinn Féin's refusal to support the Democratic Unionist Party leader in an executive office after the Stormont election.
Going head-to-head for the first time in a pre-election debate, the Sinn Féin and DUP leaders argued over power-sharing arrangements should they both be returned in March as the two main parties.
Ms O'Neill insisted yet again she was not prepared to go into government with Ms Foster until a public inquiry into the botched Renewable Heat Incentive scheme had concluded.
She said DUP "arrogance, contempt and serious allegations of corruption around the RHI scandal" had forced next month's snap election.
However, Ms Foster hit back that it was not up to Sinn Féin to decide who should lead her party. She also said that this election was "an attempt by Gerry Adams to push forward his radical agenda."
As tensions continue to simmer between the DUP and Sinn Féin, the two party leaders aired their differences face-to-face during the UTV Election Debate involving the region's five largest parties, DUP, Sinn Féin, SDLP, UUP and Alliance.
"We can go into government (after the election), but we couldn't go into government or support Arlene Foster in the position of first or deputy first minister while an inquiry is ongoing.
"The public need answers and deserve answers," said Ms O'Neill.
Ms Foster responded: "It's not a matter for Michelle O'Neill or Gerry Adams or anyone else in Sinn Féin to say who should lead the party."
Ms O'Neill hit back: "It’s not for me to say who will lead the DUP, but it's Sinn Féin's right to say who they will go into government with."
SDLP leader Colum Eastwood warned that if people vote for the DUP and Sinn Féin the region will face a lengthy period of negotiations before the institutions are back up and running.
"But if you vote for other people, we have the opportunity to form a government, no matter how difficult all these issues are. There are people who want to work together, are willing to work together, and have proven they can work together to get over some of these humps," he added.
Ulster Unionist Mike Nesbitt said Sinn Féin and the DUP "really don't want to share power, but only do it because there is a legislative duty on them to do so".
He added: "We as the Ulster Unionist Party would be willing partners, understanding the only way to move Northern Ireland forward is to work with people with whom you have differences."
Alliance leader Naomi Long accused the Ulster Unionist Party of being the "Lothario of Northern Ireland politics" during a discussion on Mr Nesbitt's decision to transfer his vote to the SDLP.
Mr Nesbitt insisted that transferring his vote to the SDLP "is the right thing to do" as "RHI is not an orange or green issue, but an issue of confidence, of good government".
Ms Long responded: "This is one of the few elections the Ulster Unionists have not fought with a pre-election pact. I think the Ulster Unionist Party has become the Lothario of Northern Ireland politics. It has hopped in and out of bed with almost every political party."
But she added: "It is good that Mike is arguing people should vote on the substance of how we do government and not along the tribal lines. That is what progress looks like."
However, Ms Foster said Sinn Féin wants to be the biggest party and wants a border poll and therefore it is a "dangerous" move for unionists to transfer votes to nationalists.
Mr Nesbitt told Ms Foster to stop playing the "politics of fear", and added that Ms O'Neill cannot be first minister unless she nominates herself as deputy first minister.
Ms Foster responded: "We are going into a period of negotiations after the election. I think it would be absolute madness to talk about who nominates who because Michelle has already made it very clear that she doesn't support me going back into office."