Sir Keir Starmer has appointed former Labour Prime Minister Gordon Brown as a special envoy on global finance, as he attempts to shore up his position after his party suffered heavy election losses.
Downing Street said the prime minister had also hired former Labour deputy leader Harriet Harman as an adviser on tackling violence against women and girls.
Brown and Baroness Harman, two influential and respected figures in the party, met Sir Keir in Downing Street before their roles were announced.
The prime minister's authority is tottering after Friday's dire election results piled pressure on him, with some Labour MPs calling for him to set a timetable for his departure.
Sir Keir has insisted he would not "walk away and plunge the country into chaos", and members of his cabinet have rallied around him.
Admitting he had made mistakes, Sir Keir said "the hope wasn't there enough in the first two years of this government" and suggested he would set out the path forward as well as "the convictions and values that drive me" in the coming days.
The prime minister is planning an attempt to reset his premiership next week by delivering a major speech and unveiling a new programme of legislation.
The appointments of Brown and Baroness Harman signal the prime minister's intentions to refresh his government.
Brown was chancellor before he became prime minister between 2007 and 2010, taking a leading role in the international response to the financial crisis of 2008.
Downing Street said Sir Keir had "committed to boosting the country's security and resilience" and in his role, Brown "will advise on how global finance cooperation can help to achieve this".
Baroness Harman was leader of the House of Commons during Brown's tenure as prime minister, and Labour deputy leader from 2007 to 2015.
Downing Street said Baroness Harman will "advise the PM on how to galvanise government to deliver for women and girls".
"The role will see her draw on work with women across Parliament to identify action needed to tackle misogyny and deliver greater opportunity for women in parliamentary and public life," No 10 said.
Sir Keir posted a promotional video on social media that showed him meeting Brown alongside Chancellor Rachel Reeves, and Baroness Harman in 10 Downing Street's back garden.
"Together, we will build a stronger and fairer Britain," Sir Keir wrote in the post above the video.
Labour ministers, MPs and officials have expressed bafflement at the appearance of two veteran Labour figures.
While both are respected by Labour MPs, their appointments have caused confusion about how figures from Labour's past signify the change the prime minister has promised.
One normally loyal minister told the BBC: "It's a joke. There is no question to which bringing these two back is the answer."
A Labour MP said: "Not sure voters in Wigan, Wandsworth, Salford or Sunderland voted Reform because they thought we needed more advisers from a different era of Labour politics. I think this shows that Keir doesn't even understand the problem, never mind the solution."
And a former Labour adviser said: "Is his plan to combat the notion that he has no ideas to just double down on that and bring in a load of other people to come up with ideas?"
Discontent over the election results is also bursting out into the open, with up to 30 Labour MPs saying publicly that Sir Keir should resign or agree to set out the process for an orderly transition to a new leadership.
Paula Barker, the Labour MP for Liverpool Wavertree, told BBC Radio 4's PM programme: "I have enormous respect for both Gordon and Harriet, but I would have had even more respect for them if they had declined the offer of, quite frankly, non-jobs and told the prime minister that it's time for a change and he should set out his timetable."
Fellow Labour MP Clive Betts told the BBC Sir Keir should "step down" in the "not too distant future" for the "good of the country and the government".
The MP for Sheffield South East said what people told him before these elections was "we might vote Labour, we've always voted Labour, we'd like to vote Labour again but not while Keir is the leader".
Betts said that people "have made their mind up" and he did not think "rebooting and refreshing" was going to "make any difference" because the public "by and large have stopped listening to Keir".
Debbie Abrahams, the Labour MP for Oldham East and Saddleworth, said she thought it was a matter of months before Sir Keir would step down as prime minister.
"He has said that he would always put the country first and we must recognise the dangers that we are in now," Abrahams said. "On this trajectory it does not look good."
But Labour's deputy leader Lucy Powell is among those insisting Sir Keir should stay put in Downing Street.
"I want him to continue as leader," Powell said.
Powell said the party needed to "reflect, to hear, to listen" and warned that if Labour did not "improve and start doing better" we are "going to see Nigel Farage walking up Downing Street in three years' time".
But she said that she thought "we would look ludicrous right now as a government to turn in on ourselves" and start debating leadership.
