The Tories are doomed to defeat at the 2015 general election if David Cameron gives in to Eurosceptic "obsessives" and allows policy to be driven by a fear of Ukip, senior MP Tim Yeo warned.
Mr Yeo believes his own pro-EU stance as well as his support for gay marriage and green policies contributed to his local party voting not to re-select him as its candidate after 30 years in the Commons.
He told the Daily Telegraph a shrinking grassroots membership was becoming increasingly "extreme" on a variety of issues after becoming the second prominent Tory ejected in a week.
And he hit out at "obsessives like the people who organise this letter-writing to the Prime Minister on negotiation".
Some 95 Conservative backbenchers signed a letter drafted by senior backbencher Bernard Jenkin calling for Parliament to be able to block any aspect of European Union legislation.
"We have a shrinking membership which means you tend to get predominantly among those remaining activists people with probably more extreme views than the average Conservative voter and that applies to issues like the EU, on issues like gay marriage." Mr Yeo told the newspaper.
"If we allow Ukip and our fear of Ukip to be what drives our policy that will lead us undoubtedly to defeat.
"I believe the right way to deal with Ukip is to become more like the traditional Conservative Party with a broad appeal to the Right and the centre.
"Clearly, we are threatened within the Conservative Party by people's obsessive interest in this issue, which is not shared by the majority of Conservative voters and certainly is not shared by the general public,"
Rather than trying to match Ukip, the Tories should be seeking to expose its policies shown as "incoherent, inconsistent, inadequate and in many places plain wrong", he said.
In comments unlikely to improve relations with local party members, the South Suffolk MP also declared himself a "v ery strong supporter" of coalition with the Liberal Democrats, which had "achieved things that couldn't have been achieved by one party on its own".
And he warned Tories not to block the HS2 rail project "for what I would see as little England reasons".
Shadow Cabinet Office minister Jon Ashworth said: "Tim Yeo is right to say that the Tory Party is shrinking, obsessive and out of touch.
"Its membership has halved since David Cameron became leader, and it is increasingly retreating back into its right-wing comfort zone.
"With a moderate MP like Tim Yeo being deselected, and ten per cent of Tory women MPs being kicked out, leaving or standing down, the Conservative Party looks less and less like modern Britain.
"Under Ed Miliband's leadership, Labour is reforming its membership and democracy to ensure that it is open and transparent."