Six Conservatives elected as MPs for the first time in 2015 have backed a European Union exit, saying the UK-EU renegotiations will achieve little.
Their statements to The Times come as Prime Minister David Cameron continues his efforts to change some aspects of the UK's membership of the EU.
An in-out referendum is due to be held by the end of next year.
The six are Anne-Marie Trevelyan, James Cleverly, Scott Mann, Craig Mackinlay, Royston Smith and Paul Scully.
Ms Trevelyan, Berwick-Upon-Tweed MP, said she didn't want "Great Britain to disappear, swallowed up by a superstate which does not have the same systems of justice or taxation.
"Sadly I believe [David Cameron] has been let down by EU leaders who are refusing to give us meaningful powers back - really free us from ever closer union."
James Cleverly, Braintree MP, said he believed Britain would be able to "prosper" outside the EU. He said he hadn't "dismissed" the renegotiation and "supported" the Prime Minister's efforts for a new deal but it had become "clear" to him the European Union "doesn't see the need for fundamental reform".
Mr Cameron said at last month's EU conference that he was a "step closer" to getting the reforms to "fundamentally change" the UK's relationship with the EU. A final deal is widely expected to be struck at February's EU summit.