Arlene Foster’s position within the DUP is almost beyond repair, Colum Eastwood has said.
The SDLP leader said he believes Mrs Foster has “let herself down” through her behaviour as DUP leader and first minister.
He also accused Mrs Foster of being “grossly offensive” in comments she recently made about the Irish language.
“I have always got on well with Arlene Foster and have been able to work well with her. Although I think the last number of months she has really let herself down.
“There was a lot of hope and promise there that she would be a different type of political leader from what the DUP have produced in the past and I think she has made a mistake of going to the extremes when there was an opportunity to change how politics was done.
“I think she has made a huge mistake and let herself down, her party down and the rest of us down. Her position is very close to being beyond repair,” he said.
Mr Eastwood added that Mrs Foster is “definitely in no position” to be leading a government whilst a public inquiry into the Renewable Heat Incentive (RHI) scandal is ongoing.
“Arlene Foster can’t just expect to step back into government. She needs to step aside until that public inquiry reports.
“If it exonerates her that is all well and good but we can’t have a government led by someone who is under a cloud of scandal.”
Mrs Foster faced a backlash from Irish speakers last week when she said the DUP would never agree to an Irish language act and that there should be a Polish language act instead, because more people in Northern Ireland speak Polish than Irish.
Alluding to Sinn Fein demands, she said: “If you feed a crocodile it will keep coming back for more.”
Mr Eastwood accused Mrs Foster of being “grossly offensive” with her comments.
“In the international agreement Irish language was recognised as being important to the whole community. This is a language we are talking about. It is fundamental to those of us who care about it,” said Mr Eastwood.
He added: “She is showing an enormous disrespect to the nationalist community and is trying to create a culture war. We need to see politics where all cultures are celebrated. Arlene Foster is doing a dishonest disservice to all those in our community who care about the Irish language.
“I don’t think the DUP understand that when they are saying no to an Irish language act they are not saying no to a particular issue, they are turning their backs on a whole community and telling people from a nationalist perspective that our position isn’t as important as people from a unionist perspective.
“I think that is a big mistake. It is about raising heckles at the mouth of an election.”