TORY former chancellor Nigel Lawson pledged yesterday to lead a “cross-party” campaign to leave the EU — but his project was immediately snubbed by trade unionists pushing for an Out vote.

The Tory peer warned that Prime Minister David Cameron would only secure “wafer-thin” reforms to the common market and called on the government to set out clear “red lines” in its attempts to renegotiate Britain’s relationship with Europe.

Speaking from his home in France, Mr Lawson said: “I would like to see a profoundly reformed European Union with reforms embedded by genuine treaty change, but it has been made quite clear by everybody in positions of responsibility in the European Union that that’s not going to happen.”

But Trade Unions Against the EU spokesman Brian Denny said that Mr Lawson was set to lead a campaign “from the political bubble.”

“As the architect of the Maastricht treaty, he won’t have any sympathy with the plight of working people,” he stormed.

“If he thinks workers are going to follow a failed Tory, he’s got another thing coming.”

Ukip donor Arron Banks has already set up one right-wing exit campaign called Leave.EU.

But Mr Lawson said that the Tories would instead invite others to join their campaign — despite it being branded “Conservatives for Britain.”

But the key figures in the Leave.EU campaign told Mr Lawson to get back in his box.

“If the Tories keep using has-beens like Lord Lawson and the other Eurosceptic rabble then that will turn off supporters,” they said in a statement.