James Brokenshire’s role was always going to be a challenging one this Parliament, with Anglo-Irish relations and the Northern Irish border set to be some of the most sensitive aspects of the Brexit negotiations.

But the mounting political crisis in the province – essentially a self-inflicted wound by the Democratic Unionist leadership – adds an extra, unexpected layer of complication.

Now the Northern Ireland Assembly wanders up to the brink of collapse on a too-regular basis, for such is the nature of the brinkmanship around which it is built. This site spent several years covering the rolling crisis caused by Sinn Fein’s refusal to implement the Coalition’s welfare reforms.

Stormont normally stays on its feet because the politicians involved derive their power, prestige, and pay from its doing so. They may have no sufficiently powerful incentive to make it actually work, but they have a very powerful motivation to keep it going.

This self-defence mechanism tried to kick in this time – it’s easy to forget now that Martin McGuinness and Sinn Fein initially tried to circle the wagons around their Executive partners when the ‘Cash for Ash’ scandal broke.

It was Arlene Foster’s refusal to step aside for an investigation, even temporarily, that finally pushed the republicans out of the Executive. It was her conduct during the election campaign that likely went a long way towards motivating nationalist voters to give the DUP a kicking. And it’s her apparent determination to stay on as leader that puts the Assembly at risk.

It suits each to monsterise the other during elections, but the DUP and Sinn Fein can do business. They’ve been doing business for ten years. The current crisis is much more about Foster than it is about any wider explanation, be it Brexit or inter-communal enmity.

Brokenshire is already lining up a series of bilateral meetings with the five main Ulster parties. He may be able to find issues on which he can entice them into forming a government – or threaten, as Peter Hain did with water rates – before the three-week time limit runs out. The Northern Irish Office is also likely looking for ways to fudge that deadline.

But if the chief sticking point is personality rather than policy his options are limited, and that’s before factoring in pressure from other Conservatives to make sure protection for ex-servicemen who served in Northern Ireland aren’t sacrificed to Sinn Fein.

The fate of the devolved institutions hinges on the power struggle within the DUP. If they insist on nominating Foster for First Minister, there may be no Executive at all.