Shadow Chancellor John McDonnell branded Tony Blair’s former spin doctor Alastair Campbell a ‘f***ing a***hole’ in furious bust-up

SHADOW Chancellor John McDonnell branded Tony Blair's former spin chief Alastair Campbell a "f***ing a**ehole" in a furious backstage bust up, The Sun can reveal.

Eyewitnesses claim the pair "almost came to blows" behind the scenes after filming BBC Question Time in Salisbury on Thursday evening.

The row kicked off when Mr Campbell asked why McDonnell “had got so personal” in front of the cameras.

He also warned Mr McDonnell that when he "destroyed Labour that should be on his conscience”.

New Labour die hard Mr Campbell raged: "you and your lot are going to ruin the Labour Party" – to which Mr McDonnell screamed back "you're a f***ing a**ehole".

Stunned onlookers said Mr Cambell's daughter had to step in to try calm things down

The showdown was also witnessed by Seb Corbyn – son of the veteran Labour leader, who works for the Shadow Chancellor.

The pair had already exchanged verbal barbs on air, and a source said last night: "It was very, very heated, nobody knew where to look."

On stage Alastair Campbell had said Jeremy Corbyn was “a disaster for the Labour party”.

Interrupting, Mr McDonnell hit back: “It’s nauseating because you are the one, above all else, who actually created the environment where no one believed a word a politician said."

He went on: “You lost us 5 million votes in that process and set us up to fail.

“The reason Jeremy was elected is because people wanted some honesty back in politics again.”

But a furious Mr Campbell accused McDonnell and Corbyn of “destroying” the Labour Party adding: “and what’s more, I actually worry you don’t even care.”

While McDonnell accused Campbell and Blair of taking Labour “to the edge”, adding that Corbyn was trying to restore “honesty and confidence in politics again”.

Despite multiple eyewitness telling confirming Mr McDonnell turned the air blue, last night his spokesman denied he had sworn.

“It didn’t happen, John just ignored Alastair when he was shouting at him, which seemed to wind him up more,” the aide said.