Shipley MP Philip Davies rubbished his party's policy on Europe as unworkable and called for an "honest debate" on continued membership.
His declaration is the first time a sitting Conservative MP has advocated a complete break with the EU and is su
re to provoke a sharp rebuke from party whips.
Even eurosceptics like Bill Cash, who wants extensive treaty renegotiations, have not gone as far.
Former Europe Minister Denis MacShane hit out last night at Mr Davies's comments, saying a break with the EU would wreck Britain.
Speaking to an audience of Conservatives and UK Independence Party members at a fringe meeting at the Tory conference in Brighton, Mr Davies said: "What I want to see is a referendum on continued membership of the EU. What do we have to fear from asking the British people if they want to continue being part of the EU?"
Labelling the EU "corrupt, inefficient, bureaucratic, anti-democratic", he said William Hague's "In Europe, Not Run By Europe" slogan did not make sense.
"We've got to accept that being in Europe is being run by Europe," he said. "And that not being run by Europe can only mean being out of Europe."
Mr Davies said he preferred to see Britain's relationship with the EU summed up by the phrase: "Trade With Europe, Not Run By Europe".
Conservative Party policy, which calls for renegotiation of some treaty elements is not an option, he declared.
"Let's be upfront about it and have an honest debate," he said.
Mr Davies claimed the policy would be popular and said it was about time someone in the party championed it.
"In all the opinion polls that I've seen there appears to be more people who want to leave the EU than vote Conservative," he said.
He also dismissed UKIP's efforts to take Britain out of the EU, saying: "The only party that's going to deliver us leaving the EU is the Conservative Party."
Dr MacShane, the Labour MP for Rotherham, said withdrawal would be a "disaster" for Britain.
He said: "If this is the true voice of Britain's Tory Party it could mean the death of Britain's economic success."
