Sir Keir refused to sack the mutinous minister who wrote in a national newspaper that care workers should be left out of restrictions to citizenship.

This morning Tapp, the migration minister, came out swinging, vowing "I won't be intimidated", after Ms Mahmood urged Sir Keir to swing the axe and cut him loose.

But far from grovelling, Mr Tapp fired back from 5,000 miles away, where he's attending a pals wedding in sunny San Francisco.

In a brazen social media broadside, the Dover and Deal MP mocked his accusers, jeering: "It's gone from 'he broke the ministerial code' to 'he stole my idea'."

He insisted the explosive Times article simply spelled out work he'd been grafting on for months, and dared critics to read it.

"I have put my views across on a policy I've been working on for months (I have the receipts)," he wrote. "Give it a read, and let's continue to discuss."

Then came the parting shot: "I won't be intimidated to drop my views. Stay classy!"

In a cheeky dig at the Westminster storm raging back home, Mr Tapp posted a sun-soaked snap, quipping that the landmark behind him was "the Golden Gate Bridge hidden by the fog".

The extraordinary public mutiny piles fresh humiliation on Sir Keir, who announced this week he is quitting - with Andy Burnham the favourite to seize the keys to No 10.

Last night, Tory shadow Home Secretary blasted the "chaos and infighting" and accused Mr Tapp of turning on his boss "in a brazen attempt to get a place in Burnham’s cabinet."

He added: "There is not a single thought for the national interest here. All these Labour Ministers care about is their own personal ambition and jockeying for government jobs. It’s beneath contempt."