On Monday, Northern Ireland Deputy First Minister Martin McGuinness resigned, effectively ending power-sharing at Stormont.
Fresh elections will be ordered in six days if Sinn Fein and the DUP can not resolve their differences over a botched renewable energy scheme.
Under the rules of the power-sharing government, which was set up as part of the peace process, his resignation forced first minister Arlene Foster, from the rival Democratic Unionist Party, to also step down.
It comes as the North's outgoing First Minister Arlene Foster says she will launch an inquiry into the "Cash for Ash" scheme, with or without Sinn Féin's approval.
Stormont faces shelling out £490 million over the next 20 years to subsidise businesses that have installed eco-friendly heating systems because tariffs were set too high and no cap set.
McGuinness explained in his resignation letter that his party, Sinn Féin, would not be nominating another candidate to fill his role. Much of Northern Ireland politics is still what one MP calls "a sectarian head count".
"There is a worsening crisis in the political institutions surrounding the Renewable Heat Incentive and serious allegations of corruption, fraud, and incompetence associated with the scheme".
Sinn Féin, which just a month ago seemed a businesslike partner of the DUP, now accuses the party of arrogance and trying to run Northern Ireland without conceding anything to republicans and other minorities. Implementing Brexit while Northern Irish politics is in disarray and each side accuses the other of trampling on the Good Friday Agreement will be impossible, especially since Northern Ireland is the only part of the United Kingdom with a land border. Foster has said she did nothing wrong.
Martin McGuinness resigns as Deputy First Minister of Northern Ireland
Martin McGuinness resigns as deputy First Minister of Northern Ireland.
"If necessary, we will take our case to the electorate", she said.
Martin McGuiness, former- NI deputy first minister. She was the minister responsible for the RHI scheme at its inception.
Mrs Foster had previously rejected calls for her to reisign.
Today I tendered my resignation.
Claire Perry (Devizes) warned she has grave concerns over the "disproportionate politically motivated investigation" of those who believed they were "just doing their job" during the 38-year military campaign to maintain security.
Brokenshire said an inquiry into the controversial energy scheme would be needed.
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