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Conservative MP Nicky Morgan has taken a swipe at the man likely to be the next prime minister, claiming Boris Johnson should have backed up the UK's ambassador to the US after emails in which he criticised Donald Trump were leaked.
After it was revealed that Sir Kim Darroch had branded the Trump administration "inept", the US President attacked the ambassador, but while most politicians publicly supported the envoy, Mr Johnson did not.
Despite Mr Johnson being the favourite to lead the Conservative Party, Ms Morgan said it was "regrettable" the former foreign secretary did not back the ambassador.
Sir Kim resigned from the post on Wednesday, saying the leak had made it "impossible" for him to carry on in his role.
Mr Trump had said he refused to work with the 65-year-old.
Asked for her opinion on the issue she said: "I'd be interested to know from Boris why (he didn't support the ambassador).
"Whether there is some history, I don't know, whether Boris had any dealings with Sir Kim when he was the foreign secretary, whether there's something else going on there."
Ms Morgan, who was speaking to Political Correspondent Paul Brand as part of his Acting PM podcast also criticised President Trump for making damaging comments about Theresa May and Sir Kim.
She said: "I think actually it is completely appalling that the US President has said such things about both the Prime Minister but also our former ambassador."
The 46-year-old Loughborough MP and former City lawyer who chairs the Treasury Select Committee, added: "It’s very very damaging that Sir Kim Darroch memos found their way into the media.
"Ambassadors have got to be able to tell governments what is going on."
Not only did she question Mr Johnson's failure to back the diplomat, who resigned after the leak, she also supported Sir John Major in his threat of legal action if the next PM shuts down Parliament to force a no-deal Brexit.
She said: "I'm very pleased that we have a past prime minister like Sir John who is still willing to stick his head above the parapet and say 'I would not put up with this."
She added how suspending Parliament "would lead to a constitutional crisis" and she'd support Sir John's legal action if it was the only way to avoid no deal.
In a lighter moment on the podcast Ms Morgan was asked who she would have in her Cabinet and her response was rather surprising.
"I would probably have George Osborne back again, not necessarily as chancellor, but he has got a great political mind," she said.
"He was always the person that was best at anticipating what position we were going to do."
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