Tory chairman Richard Holden has resigned just days after narrowly being re-elected as an MP.
Foreign secretary David Cameron has also quit as Rishi Sunak appointed an “interim” shadow cabinet in the wake of the Tories’ devastating election defeat.
Holden, who was only appointed Conservative chairman last November, won his Billericay and Basildon seat by just 20 votes in last Thursday’s general election.
It had previously been a safe Tory with a majority of more than 20,000.
Holden was imposed as candidate on the local Conservative association after the election was called, sparking a furious backlash.
He has been replaced as party chairman by Richard Fuller, who assumed the role on an interim basis.
Lord Cameron has been replaced as shadow foreign secretary by his deputy, Andrew Mitchell.
Sunak has also been forced to draft in a number of other frontbench replacements after 11 cabinet members lost their seats in the election.
The new faces include James Cartlidge as shadow defence secretary replacing Grant Shapps, and Chris Philp, who replaces Penny Mordaunt as shadow Commons leader.
Richard Fuller said: “The Conservative Party has had a difficult election and it is important that we regroup and reflect on these results.
“We should also challenge ourselves candidly and deeply on the strengths of the Conservative Party across the country and outline where improvements can be made.
“I am honoured to be asked to act as interim Chairman of the Conservative Party and to be working alongside colleagues in the Shadow Cabinet.
“United as a party we will be ready and able to hold this new Labour government to account every step of the way.”