EMILY Thornberry has become the first Labour MP to officially throw her hat into the ring to replace Jeremy Corbyn as leader.

While the party’s Brexit spokesman Keir Starmer, as well as Yvette Cooper, Clive Lewis, David Lammy and Wigan MP Lisa Nandy have all said they are considering a bid, the shadow foreign secretary said she hoped to be one of those standing in the contest.

One of the favourite for the top job is Rebecca Long-Bailey, who is backed by a number of key Corbyn allies, and would almost certainly win any vote of the membership.

Last week the party achieved its worst result at a General Election since 1935, losing 59 MPs.

In an article for the Guardian, Thornberry revealed that she had warned Corbyn against backing Boris Johnson’s calls for an early vote.

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She said Labour’s decision to back an early election was like “crackers voting for Christmas”.

Thornberry wrote: “Listening to Labour colleagues in the media over the last week, I have repeatedly heard the refrain that the problem we faced last Thursday was that ‘this became the Brexit election’.

“To which I can only say I look forward to their tweets of shock when next Wednesday’s lunch features turkey and Brussels sprouts.”

She added: “Boris Johnson proposed an election at a time of his own choosing, on an issue of his own choosing, and we went along with it – like crackers voting for Christmas.

“The Liberal Democrats agreed to it because they thought it would work in their favour, and Labour because we imagined we could change the subject. That was a total delusion.

“I wrote to the leader’s office warning it would be ‘an act of catastrophic political folly’ to vote for the election, and explained exactly why we should not go along with it.

“I argued that the single issue of Brexit should not be enough to give Johnson a five-year mandate to enact his agenda on every issue.

“Instead, I said we should insist on a referendum on his proposed deal, to get the issue of Brexit out of the way before any General Election.

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Thornberry said Brexiteer colleagues in the shadow cabinet were responsible for having insisted on backing the election.

There are some in the party who fear that replacing the MP for Islington North (Corbyn) with the MP for Islington South (Thornberry) might not help Labour win back seats in the North of England lost last week. But Thornberry said that wasn’t what was important in leading the opposition to Johnson.

Describing her time opposite Johnson in the Commons, Thornberry claimed she “took the fight to him every day and pummelled him every week”.

She added: “So when the Labour leadership contest begins, whoever is standing – and I hope to be one of the candidates – the first question shouldn’t be about their position on Brexit, or where they live in our country,” she said.

“The first question should instead be: what’s your plan for taking on Boris Johnson over the next five years?

“And do you have the political nous and strategic vision to reunite our party, rebuild our machine, gain the trust of the public, give hope to our declining towns and smaller cities, and never again waste the opportunity to take back power?”

Former Labour prime minister Tony Blair yesterday refused to give any one of the candidates his backing.

Speaking at event in London, he said the new leader would have to be someone who understood the message given to the party and to the leadership by voters at last week’s disastrous election. “The minimum threshold of credibility for any person who wants to lead and win is an acknowledgement that we have been in the wrong political place and we let the country down,” he said. “If you are not prepared to go that far, even if you win the leadership, you are not going to win an election.”