Labour has told its MPs it is the party "best placed" to re-unite the country following the UK's decision to leave the EU, a leaked document shows.
The party briefing note said leader Jeremy Corbyn, who had backed Remain, was "uniquely placed" as he understood why many people had voted to leave.
Mr Corbyn said voters had been let down by "successive governments".
But fresh calls have been made for Mr Corbyn to resign after many traditional Labour heartlands voted to leave.
BBC assistant political editor Norman Smith said members of the Parliamentary Labour Party were preparing an attempt to "oust" Mr Corbyn, with some MPs planning to call for him to "consider his position".
The leaked document said Labour was now "the only party that can meet the challenge we now face".
It said voters would now support the party because it "did not engage in project fear" - or alleged scaremongering - during the referendum campaign.
"As the party that stands up for working people, Labour is best placed to re-unite the country - we can do so as we did not engage in project fear, and we share people's dissatisfaction with the status quo, which is why we put a critical case for both remain and reform," the letter read.
It said Mr Corbyn "understands why people voted to leave, he understands people's criticisms of Europe", adding that he was "the only leader of a major party in Britain to whom that applies".
It follows criticisms of Mr Corbyn's influence on the referendum campaign and comes after voters in many key Labour areas voters backed Brexit - despite the party campaigning to remain.
The first results of the night revealed voters in Sunderland had overwhelmingly backed Leave, while Newcastle - which returned a Remain victory - had more Brexit supporters than expected.
The pattern in the north-east of England was replicated in other Labour heartlands, including areas of the north-west of England and large areas of Wales.
Mr Corbyn told the BBC there would be some "very difficult days ahead" for the UK after the vote, and warned of "consequences" for British jobs.
He called for immediate talks on Brexit to begin and said the government should invoke Article 50 of the Lisbon Treaty, which would begin the two-year process of negotiating a new trade relationship with the EU.
Following dramatic falls in the value of the pound, Mr Corbyn said Prime Minister David Cameron must work "quickly" to stabilise the economy.
However, former Labour Prime Minister Tony Blair has criticised Mr Corbyn's role in the campaign.
He told the BBC the Labour leadership was "pretty lukewarm in its support for Remain", saying Labour had failed to mobilise its supporters "to understand that this was not a protest vote".
Former Labour minister and EU commissioner Lord Mandelson said the referendum campaign showed Mr Corbyn "can't cut it" as leader.
And Labour MP Angela Smith said Mr Corbyn must "bear his share of the responsibility for the way in which he led the EU referendum campaign from a Labour perspective".
Change in approach
Meanwhile, pro-EU MP Simon Danczuk, who had the Labour whip suspended last year, said there was "no doubt" that Mr Corbyn should resign.
He told Sky News: "We've failed to get the message across to what you might describe as Labour heartlands.
"The truth is that Jeremy Corbyn just doesn't communicate well with those core voters. And the important point from that is that I think they're actually making that final disconnect with Labour."
Other Labour MPs have said the party must change to recognise concerns about immigration, the EU and wider issues.
Labour Leave campaigner Kate Hoey MP told Sky News Labour supporters were "fed up of being told they're ignorant" and the party could lose its support.
Labour former minister Ian Lucas warned the party needs a "big change in its approach" while Labour leave campaigner John Mann said the party had been "somewhat out of touch" with its supporters who were "sick to death" with what they were being offered.
There has been a renewed push in recent weeks by the Remain side to appeal to Labour voters, amid fears the party's core supporters were drifting towards Leave.
Ex-Labour leader Ed Miliband said many voters in north-east England had backed Leave because of a "deep set of issues" that have been "building for a long time".
He said voters were expressing concerns about immigration but also the "wider direction of the country".
Shadow chancellor John McDonnell told the BBC he felt that during the referendum campaign "people's grievances are being aired as well" on issues such as austerity and wage stagnation.
He said the result that was coming in was "exactly as I thought" adding there was a lot of disaffection with Westminster politics: "Some of those are Labour supporters. We have done our best to turn that around but it's been tough," he said.
But he said "we've got to listen to our own [supporters]".