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The prime minister's resigned. No-one knows who the next occupant of No 10 will be.

And today, some of the most senior figures in the Labour Party are trying to push their leader out too. There have been concerns about Jeremy Corbyn's performance for months and months. But it was his role, or lack of role, in the campaign to keep the UK in the EU, and his sacking of Hilary Benn in the middle of the night, that has given members of the shadow cabinet the final reasons to quit. Several have already gone; as many as half will be gone by the end of the day, I understand.

And documents passed to the BBC suggest Jeremy Corbyn's office sought to delay and water down the Labour Remain campaign. Sources suggest that they are evidence of "deliberate sabotage".

One email from the leader's office suggests that Mr Corbyn's director of strategy and communications, Seumas Milne, was behind Mr Corbyn's reluctance to take a prominent role in Labour's campaign to keep the UK in the EU. One email, discussing one of the leader's speeches, said it was because of the "hand of Seumas. If he can't kill it, he will water it down so much to hope nobody notices it".

A series of messages dating back to December seen by the BBC shows correspondence between the party leader's office, the Labour Remain campaign and Labour HQ, discussing the European campaign. It shows how a sentence talking about immigration was removed on one occasion and how Mr Milne refused to sign off a letter signed by 200 MPs after it had already been approved.

The documents show concern in Labour HQ and the Labour Remain campaign about Mr Corbyn's commitment to the campaign - one email says: "What is going on here?" Another email from Labour Remain sources to the leader's office complains "there is no EU content here - we agreed to have Europe content in it". Sources say they show the leader's office was reluctant to give full support to the EU campaign and how difficult it was to get Mr Corbyn to take a prominent role.

Mr Corbyn has insisted publicly that he campaigned hard to keep the country in the EU and that he made a number of speeches around the country, and attended many campaigning events. But many shadow cabinet ministers believe his performance in the campaign has shown that he is simply not capable of leading the party. One senior figure told me: "People have just had enough and are embarrassed to be part of it." Jeremy Corbyn's team are adamant that he will stand again for the leadership, and they believe the party's members would back him again.

He has had persuasive and vehement backing from the party's members who he energised last summer. But as the Labour Party reels from Thursday's result, it is not clear that support will be as solid as it was. MPs report that some of their members are contacting them to say they've changed their minds about Mr Corbyn. We'll see. It's possible that within days, both of our two main political parties will be looking for a new leader.

A spokesman for the Labour party said: "The leaks of these emails within the Labour Party are self-evidently politically motivated. This is the action of people who want to de-stabilise the leadership by attempting to demonstrate negative activity in the leader's office.

"The leaks themselves show no such thing, simply demonstrating the views of those whose emails are quoted.

"On the process of letter writing, of course it is normal practice in politics that drafts are amended. Any communications in the name of the Leader of the Labour Party are authorised by the leader's communications team and ultimately by the leader himself .

"Both Jeremy and his team worked hard to deliver his message of remain and reform. Given that the Labour Party was the only party that delivered a majority vote for the remain campaign among its own supporters, the criticisms of Jeremy Corbyn make little sense."