LONDON        -        Jeremy Corbyn has accepted his personal responsibility for Labour’s general election defeat as he gave his fullest explanation to date for the catastrophic losses that helped return Boris Johnson to Downing Street.

Writing in the Observer, the Labour leader, who has announced he will step down when a successor is elected in the spring, describes the results as “desperately disappointing”.

He says he believes Labour paid a price for a Brexit policy that was seen by some voters as an attempt to straddle the divide between remainers and leavers, and by others as wanting to rerun the referendum.

“We have suffered a heavy defeat, and I take my responsibility for it,” he says, in his first note of contrition since Labour seats fell to the Tories across the north of England and the Midlands, giving the Conservatives a majority of 80.

But, as critics tore into his leadership record, for the most part he defends it, blaming a political system that he says has been volatile since the financial crash of 2008, as well as the media and Johnson’s dishonesty, for the result.

Corbyn insists that on many issues Labour had the right answers: “I am proud that on austerity, on corporate power, on inequality and on the climate emergency we have won the arguments and rewritten the terms of political debate.”

 I am proud that on austerity, on corporate power, on inequality and on the climate emergency we have rewritten the terms of political debate

Suggesting that he believes his party would have won and he would have become prime minister if Brexit had not dominated, he adds: “There is no doubt that our policies are popular, from public ownership of rail and key utilities to a massive house-building programme and a pay rise for millions. The question is how can we succeed in future where we didn’t this time?”

As the recriminations continued within the party, and potential successors began laying out their stalls, Corbyn’s closest political ally, the shadow chancellor, John McDonnell, said he would be stepping down from the shadow cabinet.

McDonnell said that while “Jeremy was the right leader”, it was time for the party to move on under new leadership. “We will all go now. The new leader will come in place and appoint a shadow cabinet. I won’t be part of the shadow cabinet. I’ve done my bit. We need to move on at that stage with that new leader,” he told BBC News.

It is understood that Corbyn’s chief supporters will give their backing to McDonnell’s protege, the shadow business secretary Rebecca Long-Bailey, who they hope will carry the torch for the left.

Corbyn says the Tories’ central message – to “get Brexit done” – was dishonest and a con. “In towns where the steelworks have closed, politics as a whole wasn’t trusted. But Boris Johnson’s promise to get Brexit done – sold as a blow to the system – was. Sadly that slogan will soon be exposed for the falsehood it is, shattering trust even further.”

He also savages the media for its criticism of Labour under his leadership and says the party must do more “to meet this billionaire-owned and influenced hostility head-on”.

But as Labour tried to come to terms with its heaviest election defeat since 1935, an increasing number of MPs and candidates who lost their seats tore into Corbyn and his inner circle of advisers.