Brexit: Labour still split over further referendum
Labour MPs remain split over whether to back a further referendum on Brexit.
The party lost ground in the European elections, and some figures have called for a public vote to win back support, especially from Remainers.
Shadow home secretary Diane Abbott said another vote would be "the democratic thing to do" to move Brexit forward.
But Labour MPs representing Leave areas have warned against it, with Lisa Nandy saying it could be "the final breach of trust" with those voters.
The party agreed a policy at its last conference that if Parliament voted down the government's withdrawal deal with the EU - which it has effectively done three times - or talks ended in no-deal, there should be a general election.
But if it could not force one, conference agreed that the party "must support all options remaining on the table, including campaigning for a public vote".
It reiterated this position ahead of the European elections, but Labour's share of the vote fell to 14% and several senior figures criticised a lack of clarity.
Deputy leader Tom Watson said his party's Brexit stance had led to "electoral catastrophe", while former PM Tony Blair said it was not "possible to sit on the fence on Europe and appeal to both sides."
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After the results, leader Jeremy Corbyn insisted his policy had been "very clear" all along - but he sent a letter to his MPs, saying it was "clear that the deadlock in Parliament can now only be broken by the issue going back to the people through a general election or a public vote".
On Tuesday, shadow home secretary Ms Abbott said Labour was "moving towards a clearer line".
She told BBC Radio 4's Today programme: "There is no inherent contradiction between respecting the result of the referendum and having a 'People's Vote' [or further referendum], not least because it's still not sure how a People's Vote would pan out.
"I've always argued that it's perfectly possible that Leave would win again, but we're supporting a People's Vote strongly now because it's the right thing to do and it's the democratic thing to do."
But Ms Nandy, the Labour MP for Wigan, told Today the European election results showed "very few people have changed their minds", and any shift in her area of the country was towards a no-deal Brexit - backed by Nigel Farage's Brexit Party, which secured 32% of the vote UK-wide.
She added: "There is a huge frustration amongst Labour voters who voted Leave in towns like mine to see leading figures from the Labour Party out calling for a second referendum before there's been any serious attempt to implement the result of the first."
Analysis by Norman Smith, BBC assistant political editor
Jeremy Corbyn put out a letter to Labour MPs on Monday night, in which he suggested if they couldn't get a general election then there should be a so-called "confirmatory referendum" on any Brexit deal.
But many Labour folk believe it's gone beyond that - that there's no prospect of a general election, there's no prospect of a deal, and they now need to campaign openly for a referendum and for Remain.
Mr Corbyn and some of his close allies like Unite leader Len McCluskey are very, very wary of doing that because of the impact it will have in northern, Leave-supporting Labour constituencies.
And also they warn if they were another referendum, it is quite possible that the electorate might say, "Well, we've already told you once, we'll tell you again - we want to leave but this time we want no deal."
And in that climate, it seems to me Mr Corbyn is just sort of hunkering down trying to say as little as possible.
We haven't got any sort of absolute clarity from him yet on where he stands, but I think it's only a matter of time, because I have no doubt he is going to be pressed and pressed on this.
Fellow backbencher Jo Platt, who represents Leigh - the neighbouring constituency to Ms Nandy - said the party "must provide answers" for voters, "not ask them to think again".
And Caroline Flint - Labour MP for Don Valley in South Yorkshire - said another referendum was "seen by many Labour Leave areas as nothing more than a Stop Brexit mechanism".
Unite union leader and Corbyn ally Len McCluskey urged the party not to be "spooked" by the European election results and insisted another referendum "won't solve anything".
"I think [Jeremy] will repel all of those pressures coming from different sides, and he's already indicated he's going to take his time, speak to the members, the public, the unions, so we can work out a way that can take us forward," he said.
After Monday's election results, shadow chancellor John McDonnell - one of Mr Corbyn's closest political allies - told the BBC another referendum may be the only way forward.
Faced with the prospect of a "Brexiteer extremist" running the Conservative Party after the contest to replace Theresa May as leader, Mr McDonnell said Labour must back a fresh public vote to prevent a "catastrophic" no-deal scenario.
Wales' First Minister Mark Drakeford joined calls for a further referendum after Labour came third in the country, behind The Brexit Party and Plaid Cymru - making it the first time that Plaid had beaten Labour in a Wales-wide election, and only the second time it had lost such a poll in a century.
He told BBC Radio Wales: "We were doing our best to respect the result of the original referendum... I have now concluded that the only way we can try to guarantee a future for Wales that would not be a catastrophe is to put this decision back to the people in a referendum."
Scottish Labour leader Richard Leonard also said he was "more and more compelled" to believe that there should be another vote after his party lost both its seat at the European elections.