Chris Mason: Boris Johnson facing day of judgement

Will Boris Johnson survive as prime minister?

It is the only question that matters.

There are two mechanisms available to Conservative MPs to eject a prime minister who is gluing himself to the furniture in Downing Street.

The first is a flood of cabinet ministers packing it in, all at once, or one after another.

For about an hour and a half last night, it looked like that very thing might be playing out.

But it didn't.

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Two biggies, more ministers and lots of tiddlers is the current tally. Desperately awkward for a prime minister, without question.

But he has bodged together a new cabinet, the kind of emergency reshuffle no party leader wants forced upon them.

The other is a leader categorically and unquestionably losing the support of their party.

And that looks like it might very well be happening, right now.

How it manifests itself and on what timescale, who knows.

Right now, things are very fluid.

No one is in charge of events; momentum can ebb and flow incredibly quickly.

And anyone on social media who says anything definitive is guessing.

They may very well turn out to be right. But they're still guessing.

In the meantime, Boris Johnson faces what would be a tricky day in normal times.

And normal set sail from this place many years ago.

He has Prime Minister's Questions at lunchtime, and then an appointment with what is called the Liaison Committee of select committee chairs this afternoon.

Or "all his enemies in a single room" as one of his team put it to me the other day.

The blunt truth is not all of them - he's gathering more by the hour at the moment.