DUP leader Arlene Foster will attack Jeremy Corbyn as beyond the “political pale” because of his past support for Irish republicans in a speech on Monday.
She is expected to attack the Labour leader’s democratic credentials and voice support for his Conservative rival.
Mr Corbyn has said he wanted the violence in Northern Ireland to stop but refused to single out the IRA for condemnation during recent interviews.
Northern Ireland’s former first minister said: “While Theresa May is well within the political mainstream and has proven herself to be a solid and reliable unionist, Jeremy Corbyn is beyond the political pale.
“It is hard to take seriously the democratic credentials of a man who was so close to the political representatives of the IRA at the height of the Troubles.
“It is hard to see much good coming for the Labour Party from the coming election except the replacement of their leader.”
Mr Corbyn and shadow chancellor John McDonnell have faced scrutiny over their association with Irish republicans.
After becoming Labour leader in 2015, Mr Corbyn defended reaching out to republicans during the Troubles – insisting he “wanted the violence to stop”.
At lunchtime on Monday, Mrs Foster will address a meeting of the pro-Brexit Bruges Group in Mayfair on Brexit and the Union.
Although Northern Ireland voted by 56% to 44% in favour of Remain in last June’s referendum, the DUP campaigned for an exit.
She will say: “Who could deny that the situation of Northern Ireland within the UK, and indeed Ireland within the EU, will face different challenges from other areas affected by the UK’s EU exit and will require unique and tailored solutions?
“However, I do not believe that a circular argument about some ill-defined and ill-conceived so-called special status for Northern Ireland is helpful: indeed, it is more likely to be counter-productive.
“I am more interested in getting the best deal for Northern Ireland and the UK as a whole than I am in some doctrine or dogma.
“By far the best way to achieve this is to get a Stormont Executive up and running as quickly as possible.”
Meanwhile, Sinn Fein leader in the North Michelle O’Neill said the election was a political fight back and a call to action as rights were under attack.
“We have to fight back against the reckless and dangerous policies of the self-serving Tory government in London which is about forcing a disastrous Brexit on the North and dragging us against our will from the EU.
“Everyone here knows the impact that will have on our business, trade, agri-food, tourism and other sectors of the economy, with the imposition of trade tariffs, a border and denying people the freedom of movement North and South.
“It will severely undermine the progress of the past 20 years.
“The people of the North don’t want Brexit. It is unacceptable.”