He said: "If you are one of our colleagues who spends his life telling everyone Europe is awful and we should leave it, not surprisingly he has a high Ukip vote in his constituency, and half his members think that is way the Tory party should go."
He added: "The first lesson is that if you go around telling everyone your opponents are right, do not be surprised when the electorate vote for your opponents."
He made his comments as ministers said the Conservatives would be "foolish" to demand full treaty change ahead of a referendum on Europe in 2017.
Ken Clarke, the minister without portfolio and former Chancellor, said that more "strident" and "eccentric" backbench Conservative MPs were drowning out the voices expressing the more popular pro-European views that the "majority" of the cabinet holds.
Mr Clarke said that the Conservatives would be "foolish" to push for treaty change to get key reforms on Europe through before any referendum in 2017 if other alternatives were open to them. Instead, he said, they should "concentrate on the substance of reform" whichever way it was achieved.
Damian Green, the policing minister, said that it was "not obvious" that treaty change would be needed to achieve many of David Cameron's planned reforms on Europe.
He added that it while it is easier for pro-European Conservatives to "keep your head down" it would mean "handing democracy" to more vocal people who want to pull out of the EU.
Source : http://telegraph.feedsportal.com/c/32726/f/568612/s/384935a3/sc/7/l/0L0Stelegraph0O0Cnews0Cpolitics0C10A70A36130CConservatives0Emust0Estop0Eattacking0EEurope0Eor0Epeople0Ewill0Evote0EUkip0Bhtml/story01.htm