Jeremy Corbyn has been warned young people will punish him at the ballot box if he fails to fully oppose Theresa May’s Brexit deal.
An analysis of the mega YouGov poll, released over the weekend, of more than 25,000 people, shows Labour currently enjoys the support of 56% of 18 - 24 year olds.
But if the party decides to back the prime minister’s deal this drops to just 40%.
The survey also suggests the party would not get away with trying to avoid taking a position.
If Labour abstains, fails to whip its MPs, or otherwise does not fully oppose Brexit, only 42% of 18-24 year olds said they would vote for the party at the next election.
Labour has said it will vote against the prime minister’s deal when it is put to a vote in the Commons next week.
The analysis was conducted by Our Future, Our Choice (OFOC) and For our Future’s Sake (FFS) - two youth campaigns that form part of the People’s Vote organisation pushing for a second Brexit referendum.
Jason Arthur, co-founder of FFS, said the figures showed the “massive risk” Corbyn faced if he failed to oppose Brexit.
The YouGov survey sampled over 2,000 18 - 24 year old’s - the largest ever survey specifically on Brexit and young people since the 2016 referendum.
Corbyn has come under increasing pressure to back a second referendum as the prospect of a no deal Brexit increases.
But the Labour leader has said his priority is to secure a general election and lead the UK out of the EU on his own terms.
The party has only committed to possibly holding a referendum, which could stop Brexit, should it be unable to force a general election.
Tensions between People’s Vote and the Labor Party were further exposed on Sunday when Shadow foreign secretary Emily Thornberry accused some in the campaign of seeking to “slap the Labour Party around”.
The government will begin broadcasting radio adverts on Tuesday to help people prepare for Brexit, focusing on topics including passports, visas, healthcare and driving in the EU.
They will provide information on both no-deal and other Brexit scenarios, and will be followed by billboards and posters in the coming weeks.