Shadow chancellor John McDonnell has said he will step back from frontline politics after a new leader is chosen for the Labour Party.
It comes after a disastrous election for the party, which saw its worst results since the 1930s.
Jeremy Corbyn is expected to stand down “early next year” when a successor has been chosen by the party.
Speaking to the BBC on Saturday, Mr McConnell said once that happens he will no longer be part of the shadow cabinet.
Asked whether he backed the wrong leader and whether he should resign, he responded: “I didn’t back the wrong person because Jeremy was the right leader.
“We could have won in 2017. Things moved on, Brexit dominated everything and that was the horns of a dilemma we were on.
“The new leader will come in place, appoint the 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, and I think we will be in a position [to be] learning lessons, listening to people and constructing a broad coalition right the way across the country.”
He added: "The new leadership coming in, I think, will enable us to move forward on the key issues – getting a Brexit deal that works for all of us, tackling these grotesque levels of inequality.
“But the big one... is climate change and my fear is five years of a fossil fuel-backed government under Boris Johnson means we will miss this five-year opportunity of saving our planet.”
Mr Corbyn has been attacked by former Labour MPs and party veterans after the poll.
Ex-MPs Anna Turley and Helen Goodman, and last night former cabinet minister Jack Straw were the latest to criticise Mr Corbyn.
Ms Turley, who lost her seat in Redcar on Thursday, told BBC Radio 4's Today programme that Mr Corbyn was "absolutely" more of a reason than Brexit for her constituents voting for another party, adding: "In my constituency, even though it was a 67 per cent Leave constituency, it was four to one the leadership over Brexit.
"I mean obviously the issues run deeper than that, the Labour Party is bigger than just one person, but the reality is there were issues around our perception around competence."
Ms Goodman, who was defeated in Bishop Auckland, told BBC Radio 4's Today Programme "the biggest factor was obviously the unpopularity of Jeremy Corbyn as the leader".
Despite criticism, Mr Corbyn has claimed he did "everything he could" to get Labour into power but said the election was "taken over by Brexit".
