Jeremy Corbyn and John McDonnell have apologised over Labour’s “catastrophic” defeat in Thursday’s election, which saw them lose 59 seats.
Mr Corbyn said he was “sorry that we came up short”, while Mr McDonnell told the BBC he “owns this disaster”.
The leader and shadow chancellor said they would step down in the new year.
The race for their replacements has already begun, with Wigan MP Lisa Nandy saying for the first time she was “seriously thinking about” running.
Labour suffered its worst election result since 1935 and saw its vote share fall by eight points.
The Conservatives won a Commons majority of 80 – the party’s biggest election win for 30 years – sweeping aside Labour in its traditional heartlands.
Mr Corbyn apologised to Labour supporters in two articles in the Sunday papers, calling it a “body blow for everyone who so desperately needs real change in our country”.
Writing an open letter in the Sunday Mirror, he said he took his “responsibility” for the result, but insisted he remained “proud” of the party’s campaign.
He doubled down in the Observer, saying his own election campaign had successfully re-set the terms of debate and his manifesto would be seen as “historically important”.
But Mr McDonnell has argued “it’s on me” as he apologised for the performance, on the BBC’s Andrew Marr Show.
The shadow chancellor said he was sorry for “not being able to articulate” the party’s campaign message ahead of the poll.
However, he also blamed the “media portrayal” of Mr Corbyn, saying “of course the system will throw the kitchen sink at you” if you challenge it.
Former Labour MP Caroline Flint – who lost her seat on Thursday – placed much of the blame at the leadership’s door.
She also told Sky’s Sophy Ridge that “ardent Remainers” in the party, such as shadow Brexit secretary Sir Keir Starmer and shadow foreign secretary Emily Thornberry, “contributed to sacrificing” seats, with the “balance in voices” going too far away from Leave voters.
She accused Ms Thornberry of telling one her colleagues from a Brexit-backing area: “I’m glad my constituents aren’t as stupid as yours.”
Ms Thornberry has not yet responded to the comment.
Ms Flint added: “I don’t believe anybody who have been the architects of our European policy in the last few years is credible to be leader. I don’t think they can win back these seats.”