Video report by ITV News Political Correspondent Paul Brand
Labour deputy leader Tom Watson launched his biggest push yet for the party to fully commit to supporting a second referendum.
Speaking on Monday morning, he said a second vote is "the only tool" to break the Brexit deadlock, adding: "Our members are remain, our values are remain, our hearts are remain... we need to be loud and proud in support of Europe."
Mr Watson said “our future doesn’t need to be Brexit” as he argued that the European Union’s values were shared by Labour and its supporters.
Labour MPs react to Watson's announcement
As Mr Watson gave his speech, Labour Party chairman Ian Lavery tweeted: "Brexit has turned this country into a toxic nation. However ignoring the 17.4m leave voters isn't politically smart nor indeed particularly democratic. Is it? #simplysaying"
Responding to Mr Lavery's tweet stating that opposing Brexit would mean "ignoring" voters, Labour MP Wes Streeting wrote: "4 in 10 Labour members didn't vote Labour.
"We just got the worst national election result since 1910.
"We just lost council seats that Miliband won on the same day that the Tories won a majority for first time since 1992.
"I'm missing the political genius here #simplysaying."
Last week, Lavery hit out at Remainers in the party, dismissing them as "left wing intellectuals" who were "sneering at ordinary people" in traditional Labour heartlands who voted for Leave.
In an earlier tweet, Birmingham Yardley MP Jess Phillips said she agrees with the party's deputy leader on his second referendum stance.
She reshared a tweet from Redcar MP Anna Turley in which she said Watson was saying "what should have been said in 2016".
Why has Watson started a new offensive for a second vote and what reaction is he likely to face?
Labour leader Jeremy Corbyn has been resisting pressure to fully embrace a second referendum, amid heavy criticism of the party’s dismal showing in last month’s European elections.
Confusion over the party's position as supportive of another referendum in certain limited circumstances, was widely blamed for a poor performance which saw it beaten into third place behind the Brexit Party and the Liberal Democrats.
Mr Watson is likely, however, to face a strong push-back from allies of Mr Corbyn, determined to resist any change of policy.
He said: "We cannot go on dismissing one another’s right to speak and questioning one another’s motives and intentions."
"Some people have begun to equate support for Europe with class identity, I don’t think that’s right or helpful.
"The majority of Labour people are supportive of Europe – and that support is not dictated by social class."
"I love Europe because I’m a democratic socialist,” he said.
"Socialism is achieving common causes by the strength of collective endeavour.
"That’s what Europe is. We’ve shied away from saying these things for too long.
"But now, as we stare down the barrel of a Boris Johnson premiership, we really must."
Mr Watson added that the relationship with Europe was about "more than economics" or political co-operation.
"It’s about what kind of country we are. What we want for our children: what we’re able to bring them up to be.
"So those of us who love Europe should take pride in making this argument," he said.
"We must bring the public back into this decision and we must argue strongly to remain.
"Our future doesn’t need to be Brexit. We can change the future.
"We can put Britain back at the heart of Europe again.
"We can be proud of leading the fight for a fairer and stronger future, together.”