Theresa May will be confronted face to face by Sinn Fein’s Stormont leader Michelle O’Neill over her proposed deal with the DUP when the two women meet in Downing Street on Thursday.
Sinn Fein, along with the other four main parties in Northern Ireland, has been invited to Number 10 in attempt to break the deadlock over power-sharing talks.
But Mrs O’Neill has already made it clear she will raise the issue of the DUP deal when she meets the Prime Minister.
She hinted that she might demand the scrapping of the DUP deal if it “undermines” the Good Friday Agreement.
There is no agreement yet between the Conservatives and the DUP.
Mrs May is already discovering the perils of dabbling in Northern Ireland politics, and has been told by the former Conservative prime minister Sir John Major that her proposed pact with the DUP could put the peace process at risk.
The 1998 Good Friday Agreement commits the UK and Irish Governments to demonstrate “rigorous impartiality” in their roles as co-guarantors of the peace process.
Mrs O’Neill said: “I will be making it very clear that any deal between the Tories and the DUP cannot be allowed to undermine the Good Friday and subsequent agreements.
“It’s imperative that both [British and Irish] Governments recommit to the word, spirit and implementation of the Good Friday Agreement if there is to be any prospect of re-establishing the [Stormont] Executive.”