NICOLA Sturgeon's opposition to Brexit is key to forcing a second EU referendum, former Labour cabinet minister Andrew Adonis has said.

Adonis spoke out in his first interview with the Scottish media after sensationally quitting as the UK Government's infrastructure tsar. He said he wanted to “work closely” with Sturgeon to make Westminster hold a second referendum.

Speaking to the Sunday Herald, Lord Adonis said: "Her voice is a powerful one and I hope I can work closely with her in forcing Theresa May to let the people of the UK make the final decision on the Brexit deal that's negotiated."

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The dramatic intervention came amid growing pressure for a fresh Eu referendum. Adonis said Sturgeon had been pivotal in exposing the "lunacy" of Brexit with her consistently pro-EU stance as one of the leading UK voices against a hard Brexit. The former transport secretary said the SNP's approach could also derail the EU withdrawal bill in the Commons.

Adonis said Sturgeon had “done absolutely the right thing” in seeking to keep the UK in the single market.

Sturgeon has said a second EU referendum may prove “irresistible” amid concerns about the direction of the UK Government's Brexit negotiations.

There have also been claims that a constitutional crisis is looming between Holyrood and Westminster, with MSPs warning that they will reject the withdrawal bill in its current form due to the threat to Scotland's devolved powers. Holyrood's finance and constitution committee voted unanimously against recommending MSPs back the bill.

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Adonis, a senior Labour peer, praised the way Sturgeon had handled her opposition to a hard Brexit.

He said: "Nicola Sturgeon has done absolutely the right thing in pursuing her position on a soft Brexit.

"She's made clear the lunacy of leaving the EU by constantly arguing for a soft Brexit and for European integration.

"The First Minister has done a good job at standing up for Scotland in the Europe debate."

Adonis, who served as a minister under Tony Blair and Gordon Brown, said that the “tide is turning” in England against Brexit.

He has emerged as an unlikely ally of Jeremy Corbyn after he rocked the UK government with his resignation as infrastructure tsar.

Despite his Labour affiliation, Adonis was appointed in 2015 by the then chancellor George Osborne as head of the National Infrastructure Commission, the body that makes recommendations to the government on major projects such as high-speed rail.

However, he quit last month after he accused Tory ministers of promoting a hardline right-wing Brexit ideology and wasting taxpayers' cash on a bail-out of Virgin rail and Stagecoach for East Coast trains.

Meanwhile, Adonis said Sturgeon was “right to keep the pressure” on Corbyn to shift Labour’s position towards backing for a softer Brexit.

He said that tactic could prove decisive in defeating the Tory government's Brexit bill in the Commons.

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Adonis claimed that if Labour MPs joined with the SNP, Lib Dems and pro-EU Tory rebels such as former Attorney General Dominic Grieve, Theresa May's minority government would be defeated even if it was backed by the DUP.

Adonis said Grieve had "done a superb job" and was part of the "real opposition" after he helped inflict a defeat on his own party over Brexit before Christmas.

However, Adonis said Sturgeon calling out Labour over the issue could prove decisive.

He said he was convinced Corbyn would embrace outright opposition to a hard Brexit.

Labour's leaderships at Westminster and Holyrood has stressed a need to retain "the benefits" of the single market and the customs union, but has stopped short of backing full membership.

However, Adonis said Corbyn's youth supporters, as well as Sturgeon could force a change in policy.

He added: "Jeremy Corbyn has an almost cult-like status among many young people.

"Young people making the argument that Jeremy Corbyn should support a referendum could make all the difference.

"Slowly but surely I'm sure Jeremy Corbyn will change his position."

Adonis said he expected Scottish Labour to make a similar policy shift.

He said: "Nicola Sturgeon is right to keep the pressure on Labour over this.

"There is overwhelming support for continued EU membership among Labour Party members

"What Grieve and the Tory rebels do will also matter in terms of numbers in the Commons.

"Labour voting against the bill means Theresa May's government would not have a majority even with the support of DUP MPs."

Meanwhile, Adonis vowed that he would wreak havoc on the Tories, when the Brexit bill comes to the House of Lords.

He said: "I'm very active on the Labour benches and on the EU Withdrawal Bill, I'll make the government's life a misery. They won't have seen anything like that sort of opposition yet."

However, Adonis said he wanted to forge an alliance with Sturgeon to get a second EU referendum called.

The hopes of anti-Brexit campaigners were ignited after former Ukip leader Nigel Farage told his supporters to prepare for a second referendum to "kill off the issue for a generation".

Nicola Sturgeon hinted that she may be ready to back a second EU referendum, in an interview last week.

“As the situation develops the argument for giving people a say on the final outcome may become irresistible,” she said.

Adonis, who is one of the leading advocates of a second referendum, said: "I hope that during the course of the campaign against Brexit that the First Minister will strongly argue for a second referendum. The tide is turning against Brexit in England and I feel there is now a big opportunity to push for a second referendum before 2019.

"I very much hope that the First Minister will strongly support calls for a second referendum before the UK exits the EU. What is it that Theresa May is frightened of here?

"I'm looking forward to campaigning alongside the First Minister."

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In response to Adonis, a spokesman for Sturgeon said: “The First Minister has made clear that, short of remaining in the EU, the least damaging option will be keeping our place in the single market.

“Andrew Adonis is one of the Labour voices who is speaking up against that threat. But the failure of the Labour leadership – at Westminster and in Scotland – to properly oppose the Tories on Brexit is utterly inexcusable.”

However, a UK Government spokesperson, hitting back at Adonis, said: "The British people voted to leave the EU.

"The UK Government is clear that it is now its duty to implement the will of the people and so there will be no second referendum."