Jeremy Corbyn has confirmed for the first time that he is prepared to campaign for Britain to quit the European Union if he becomes Labour leader.
The veteran leftwinger suggested at the final party hustings event that he was ready to join an Out campaign if David Cameron ‘trades away’ workers’ rights, environmental protection and fails to crack down on Brussels-backed tax havens.
In his clearest signal yet that he would side with trade unions and others on the Left who object to a ‘bosses’ Europe’, Mr Corbyn said that he would not give the Prime Minister ‘blanket’ support for his renegotiation of powers.
At the hustings in Warrington, Mr Corbyn, Andy Burnham, Yvette Cooper and Liz Kendall were asked directly if they would ‘rule out voting No or campaigning for No’ ahead of the 2017 referendum.
The Islington North MP replied: “No I wouldn’t rule it out...Because Cameron quite clearly follows an agenda which is about trading away workers’ rights, is about trading away environmental protection, is about trading away much of what is in the social chapter.
“The EU also knowingly, deliberately maintains a number of tax havens and tax evasion posts around the continent - Luxembourg, Monaco and a number of others - and has this strange relationship with Switzerland which allows a lot of European companies to outsource their profits to Switzerland where tax rates are very low.
“I think we should be making demands: universal workers’ rights, universal environmental protection, end the race to the bottom on corporate taxation, end the race to the bottom in working wage protection.
“And I think we should be making those demands and negotiating on those demands rather than saying blanketly we’re going to support whatever Cameron comes out with in one, two years’ time, whenever he finally decides to hold this referendum.”
A YouGov poll last week put Mr Corbyn in first place in the Labour leadership race among party members and he has the largest number of local constituency party nominations of all the candidates.
Mr Corbyn said that European Union’s treatment of the left-wing Syriza government in Greece ‘shows just how economically driven they are’, with privatisation and austerity making the country’s plight even worse.
His stance echoes that of some trade union leaders, as well as the TUC’s Frances O’Grady, who have warned that any attempt by Mr Cameron to undermine the UK’s worker rights would push people towards a ‘No’ vote.
At the height of the Greek default crisis, author and campaigner Owen Jones recently declared that it was now time for the Left to ‘reclaim the Eurosceptic cause’ and consider a campaign for ‘Lexit’.
Mr Jones has argued that ‘without a prominent Left Out campaign, UKIP could displace Labour right across northern England’. Today, Mr Corbyn also heaped praise on Mr Jones for his defence of the working classes.
None of the other candidates said they were prepared to join the ‘No’ campaign in the in-out referendum, which is due to take place by the end of 2017.
Ms Cooper said that two million British jobs relied on EU membership and that while Mr Cameron was wrong to try to undermine worker rights, ‘none of that is solved by saying that we are going to pull out’.
“Because actually what we need to do is be in there arguing for those stronger employment rights, right across Europe and also saying look if David Cameron wants to get rid of them, then that’s all the more reason for a Labour government to get elected and put them back.”
Ms Kendall said: "I always want us to remain part of the European Union. Remember what happened the last time round, the Tories had the opt-out of the social chapter. We won the election, we got back in and we brought in the social chapter.
"That's the difference Labour in government makes. A party that wants to win elections so that we can put our principles into practice and not just protest from the sidelines.
She called for a strong ‘Yes’ campaign with trade unions, green groups and young people making the case for EU membership.
Mr Burnham said "on balance our national interest always lies with staying in" but pointed out he had called for a Labour 'Yes' campaign that learned from the Scottish independence referendum.
Labour was split over joining the Common Market in the 1970s and early 1980s, and some Labour MPs have long argued that Britain would be better off out of a free-market trading bloc that promotes business and corporate interests.
Some have already warned that if the party were to back an 'Out' campaign under a new leader, it could split over the issue just as it did under Michael Foot, when the SDP was created as an explicitly pro-European party.
The Warrington hustings, chaired by The Huffington Post Uk's Paul Waugh, also saw the Shadow Health Secretary explain why he had abstained in the recent vote on the Tory welfare bill, declaring he didn't want to 'plunge the party into civil war'.
In the deputy leadership hustings which followed, Angela Eagle rounded on Tony Blair for his remark that those who sympathised with Mr Corbyn needed to get a heart 'transplant'.
Ballot papers for both the leadership and deputy leadership elections go out in just over a fortnight's time and the winner will be announced on September 12.