The gaffe by the shadow health secretary is his second in a week after he came out in support of strike members of the RMT union who are bringing Britain’s trains to a halt next week.
The reaction to his support for the militant trade union extremists was widely condemned and led to questions about his ambitions to replace Sir Keir should the Labour leader be forced to resign.
It is understood that in private Mr Streeting apologised to his shadow cabinet colleagues for his words which embarrassed the Labour leadership.
On his Tweet attacking the Prime Minister, a Conservative source said: “This is deeply embarrassing for Wesley who has shown a total lack of guts in his refusal to condemn next week’s rail strikes. He should delete the tweet and apologise.”
Mr Streeting is currently second favourite with the bookies to take over from Starme and the leading candidate who is an MP.
Only Manchester Mayor Andy Burnham is ahead of him in the odds.
He was identified as Starmer’s successor by pro-EU Rejoiners in Westminster and the media after the Labour leader’s future came into doubt following Durham Police reopening the investigation into Beergate on April 30 last year.
Sir Keir has said he will resign if fined for the event where more than £200 of curry was consumed and washed down with beer.
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