Former minister Tim Yeo has lost his battle to be re-selected as the Tory candidate in South Suffolk.
Despite backing from Prime Minister David Cameron, Mr Yeo lost out in a secret ballot of 600 members of his constituency party after the association's executive committee voted not to re-adopt him for next year's general election.
In a statement, Mr Yeo said: "It has been a privilege to serve as MP for South Suffolk since 1983. I will continue to work for all my constituents until the general election next year.
"I am immensely grateful to all those Conservative Party members who voted for me to continue as their MP. I now ask them all to campaign for my successor with the same loyalty and dedication they have shown to me.
"I will give my full and unqualified support to whoever is chosen as the candidate here in South Suffolk. I wish him or her every success."
Party sources said there was an 82% turnout in the ballot, but refused to give details of the margin of defeat. The count - carried out at Tory HQ in London - came just days after another senior Tory colleague, Anne McIntosh, lost a similar de-selection fight in her Thirsk and Malton seat in North Yorkshire.
The South Suffolk executive declined to re-adopt Mr Yeo in December just a month after the Commons sleaze watchdog cleared him of breaking parliamentary rules on lobbying.
The MP had temporarily stood aside as chairman of the influential Energy and Climate Change Committee while the investigation was carried out in the wake of a newspaper "sting".
Reports have suggested his de-selection reflected frustration among some members that he was not devoting enough time to the constituency rather than concerns over the standards inquiry.