Britain's Thatcher-era finance minister Nigel Lawson says he will lead a campaign by a group within Prime Minister David Cameron's Conservative Party to fight for an exit from the European Union.
Writing in The Times newspaper on Thursday (local time), the eurosceptic who served as chancellor under Margaret Thatcher from 1983 to 1989, said Cameron's plans to press for reforms within the EU were "wafer thin" and unlikely to succeed.
As president of the "Conservatives for Britain" group, he said he will call for Britain to leave the 28-nation bloc "unless there is real reform".
"Unfortunately the EU is just not set up either to reform itself or to accommodate demands for power to be returned to its member countries and their people," Lawson said.
Cameron is seeking to renegotiate the terms of Britain's EU membership before holding an in/out referendum by the end of 2017.
He has said he will push for broad changes including protecting sovereignty, opting out of the EU's commitment to "ever closer union", limiting access to benefits for migrants, and boosting competitiveness.
Lawson claimed Cameron had already "watered down" some of his demands and called on the prime minister to set out some "red lines".
"My priorities would be fourfold – the end of the automatic supremacy of EU law over UK law, the ability for the UK to negotiate its own free trade deals with fast-growing countries such as India and China, the ability to control immigration from other EU countries to the UK, and the explicit renunciation by the EU of its absolute commitment to 'ever-closer union'," he said.
He urged colleagues to join his campaign, warning that otherwise "less moderate, xenophobic voices will dominate the debate".
The rallying cry comes as the UK Independence Party seeks to unite anti-EU factions in a new group, "Leave.EU".
Speaking at UKIP's party conference last week, leader Nigel Farage said the anti-EU camp was "on course to win the most historic and important political victory in any of our lifetimes".
Until recently, opinion polls suggested that those against a so-called "Brexit" were in the majority, but two recent surveys have put the anti-EU camp ahead.
In a YouGov poll conducted for The Times, 40 percent said they would vote in favour of leaving the EU, while 38 percent said they would vote to stay in.
Britain's opposition Labour Party set up the "Labour Yes" group earlier this year to shore up support for the pro-Europe campaign.
But divisions remain within the party, with MP Kate Hoey, a long-time Europe critic, setting up the rival "Labour for Britain" group to support an "out" vote if new EU membership terms are not met.