At least 100 Tory MPs are expected to end up standing down at the general election, HuffPost UK has learned.
The unprecedented exodus comes as the party braces itself for a heavy defeat after 14 years in power.
Northern Ireland secretary Chris Heaton-Harris became the 65th Conservative to confirm they will not seek re-election when the country goes to the polls later this year.
In a letter to Rishi Sunak, the Daventry MP said: “I feel the time is right for me to look for new challenges.”
Another Tory who is standing down at the election said Heaton-Harris will definitely not be the last to confirm they will not stand again.
The MP said: “We’ll end up with at least 100 standing down and going off to do something else with their lives.”
A senior backbencher said: “One hundred sounds about right to me, there will certainly be many more announcing their intentions in the months to come.”
That would be even more than the 75 Tories who stood down before the New Labour landslide of 1997.
Among the big-name Conservatives who are quitting are Sajid Javid, Theresa May, Kwasi Kwarteng and Ben Wallace.
A new opinion poll published today provided further evidence that Labour is heading for victory on a similar scale to 1997 this time around.
The Deltapoll survey put Labour on 45%, with the Conservatives on 23%, 4 points down on a week ago.