An election will be called in Northern Ireland this evening as Sinn Fein insist they will not nominate a replacement for Martin Mc Guinness as Deputy First Minister.
He resigned after the DUP first minister, Arlene Foster, refused to stand aside while an investigation is carried out into a botched energy scheme that could cost the taxpayer millions.
After tonight's deadline, the secretary of state, James Brokenshire, has what the rules call - "a reasonable period" - to set an election date.
He says this is about the parties.............
The collapse of the Stormont Executive will add further complications to Ireland's response to Brexit.
Over the weekend British prime minister Theresa May let it be known that she favours a so-called Hard Brexit if that's what it takes to get the UK out of the EU.
That would mean pulling out of both the EU's customs union AND the single market - making it much harder to maintain an open border along the North.
Ireland would have hoped to get the North on board to resist that option - but as of this evening, there won't be a government in Stormont.
Today marks the deadline for trying to fill the positions of First and deputy First Minister - and barring a major last-minute u-turn, Sinn Fein will refuse to return the DUP back into power by nominating someone to serve alongside Arlene Foster.
That will leaves a major power vacuum just when Brexit is about to begin, and with no certainty that a new government can be formed afterwards.