The crisis in the Red Sea is entering its third week. The Houthi rebels in Yemen are not backing down. And the world's supply chains are now feeling the squeeze. This is not just a Middle Eastern problem. It is a Westminster problem.

Whitehall sources tell me the situation is 'grave.' The Prime Minister's private office has been holding daily crisis calls. The Foreign Office is scrambling for a diplomatic off-ramp. But the rebels are demanding a ceasefire in Gaza. That is a non-starter for Number 10.

Downing Street is in a bind. The economy is already flatlining. Inflation is sticky. Now this. Retailers are warning of empty shelves by March. Car manufacturers cannot get parts. Energy prices are creeping up again. The Treasury is modelling worst-case scenarios. They do not make for happy reading.

But here is the political rub. The government is fighting a two-front war. On one side, the environmental lobby is furious. They say the crisis is a direct result of oil dependency. On the other, the Brexiteer wing of the Tory party is smelling blood. They see this as proof that globalism is fragile. That Britain needs to go it alone.

There is chatter of a backbench rebellion. A group of MPs are drafting an amendment to the Trade Bill. It would force the government to prioritise domestic food production. The whips are worried. They cannot afford a defection. The majority is already razor-thin.

And then there is the US. Biden is distracted by an election year. The Saudis are playing their own game. The Egyptians are furious about lost revenue. No one is coming to save us.

The real question is this. How long can Sunak hold the line? The polling is already awful. Labour is 20 points ahead. A prolonged crisis could be the final nail. The ERG is sharpening its knives. The 1922 Committee is monitoring the temperature.

One senior Tory MP told me this: 'If this goes on another fortnight, there will be blood.'

So watch this space. The next 48 hours are critical. There is a cabinet sub-committee meeting tonight. Decisions are being made. But in the dark corners of Whitehall, the whispers are getting louder. This crisis is not going away. And neither are the knives.