Senior Labour figures have called for an urgent change in the party’s Brexit policy after “disastrous” EU election results.
As Labour fell to third place, deputy leader Tom Watson said: “We need a change of direction urgently.”
Shadow foreign secretary Emily Thornberry said Labour should now campaign to remain in the EU.
But Labour leader Jeremy Corbyn said the party would “bring our divided country together”.
With some results still to declare, Labour was on course for less than 15% of the vote – worse than the party’s previous low in 2009 – and a fifth place finish in Scotland.
In a statement, Mr Watson said the likely election of a “hardline Brexiteer” as Conservative leader put additional pressure on Labour to change its approach.
He said: “It is now a serious concern that the next Tory Prime Minister runs down the clock until 31 October and crashes out of the EU with no deal. We cannot let that happen.
“Labour is rightly calling for a general election. But we cannot go into an election with our current Brexit position.”
Ms Thornberry told the BBC that Labour’s EU election campaign lacked clarity on Brexit. “We were not clear on the one single thing that people wanted to hear,” she said.
She said Labour had done “everything we can to try and get a decent policy on leaving the European Union” but now faced a Conservative leadership which would “insist” on a no-deal Brexit.
The party must be “equally clear” by supporting another referendum and campaigning to remain, she said.
Former Labour communications director Alastair Campbell told the BBC he had voted for the Liberal Democrats “for the first time in my life”.
“I felt on this issue the Labour party has let its own supporters down, its members down and the country down in the way that it has failed properly to develop a policy that the party and country could unite around.”
‘Challenging on the doorstep’
However Mr Corbyn blamed the results on “Tory failure” to deliver Brexit, turning the EU elections into a “proxy second referendum” where single-issue parties such as the Brexit Party would thrive.
He said: “With the Conservatives disintegrating and unable to govern, and parliament deadlocked, this issue will have to go back to the people, whether through a general election or a public vote.
“Labour will bring our divided country together so we can end austerity and tackle inequality.”
But Labour’s MPs are divided on Brexit with some – like former leadership contender Owen Smith – supporting a change in Labour policy to back remaining in the EU.
Other Labour MPs in Leave-voting areas – like Don Valley MP Caroline Flint – said it would be a “mistake” for the party to appeal only to Remain voters.
Labour chairman Ian Lavery told BBC Radio 4 that the results were disappointing, but that the Conservatives performed worse, suffering a “whiteout”.
He said: “We’re the party who try to bring everyone together, it’s been challenging trying to get that view across on the doorstep.”