The Liberal Democrats overturned a 24,000 Tory majority to win in Tiverton and Honiton, while Labour reclaimed Wakefield in the contests triggered by the resignation of disgraced Conservatives.
Mr Dowden said the results mark the “latest in a run of very poor results” for the Tory party and said in his letter to the Prime Minister that “someone must take responsibility”.
Who is Oliver Dowden?
Oliver Dowden is the Conservative MP for Hertsmere, in Hertfordshire, where he has served since May 2015.
He was appointed a Commander of the Order of the British Empire (CBE) in the 2015 Dissolution Honours List and previously served as Secretary of State for Digital, Culture, Media and Sport from 2020 to 2021.
He was previously Paymaster General and Minister for the Cabinet Office from 2019 to 2020, and Parliamentary Secretary at the Cabinet Office from 2018 to 2019.
In September 2021, he was appointed by the Prime Minister as Chairman of the Conservative Party.
Prior to becoming a member of the government, Mr Dowden chaired the All-Party Parliamentary Group for British Jews and served as an officer of the Conservative Friends of Israel.
Why did he resign?
Mr Dowden quit as chairman of the Conservative party following two by-election defeats, saying the Tories “cannot carry on with business as usual”.
His resignation came after a dramatic swing of almost 30% from the Tories to the Liberal Democrats saw Richard Foord secure a majority of 6,144 in Tiverton and Honiton.
The new Lib Dem MP used his acceptance speech to call for Mr Johnson “to go, and go now”, claiming his victory had “sent a shockwave through British politics”.
Meanwhile, Simon Lightwood was elected in Wakefield with a majority of 4,925 on a swing of 12.7% from the Tories to Labour.
Wakefield was one of the so-called red wall seats won by the Tories in the 2019 general election after being Labour since the 1930s.
Mr Lightwood said: “The people of Wakefield have spoken on behalf of the British people.
“They have said, unreservedly: Boris Johnson, your contempt for this country is no longer tolerated.”
What did he say in his resignation letter?
In his resignation letter to the Prime Minister, Mr Dowden wrote: “It is with great sadness that I must resign as Chairman of the Conservative Party with immediate effect.
“Yesterday’s Parliamentary by-elections are the latest in a run of very poor results for our party. Our supporters are distressed and disappointed by recent events, and I share their feelings.
“We cannot carry on with business as usual. Somebody must take responsibility and I have concluded that, in these circumstances, it would not be right for me to remain in office.”
“It has been an honour to serve in your Cabinets as Party Chairman, Culture Secretary and Minister for the Cabinet Office.
“In particular, I want to take this opportunity to pay tribute to our excellent Conservative volunteers and staffers who work so tirelessly for our cause. They are the backbone of our great party and deserve better than this.
“Finally, I want to emphasise that this is a deeply personal decision that I have taken alone. I will, as always, remain loyal to the Conservative Party.”
Has Boris Johnson responded?
Boris Johnson has said he will “keep going” after his authority suffered a series of blows by the double by-election defeat which triggered the resignation of Mr Dowden.
The Prime Minister acknowledged on Friday that losing the former Tory stronghold of Tiverton and Honiton to the Liberal Democrats and surrendering Wakefield to Labour was “tough”.
However, speaking 4,000 miles away in Rwanda, where he is at a Commonwealth summit, he vowed to “listen to voters” after the dramatic swing away from the Tories in the Devonshire constituency.
A Tory party source said Mr Johnson was in his hotel pool by 6am Kigali-time and was surprised to receive the call from Mr Dowden warning him he was about to resign.
Mr Johnson went on to hold his typical daily meeting with Chancellor Rishi Sunak and with chief whip Chris Heaton-Harris, the source added.
Despite the political drama, Mr Johnson was said to be planning on staying the course in Rwanda before heading to a G7 summit in Germany.
The source added: “To not be at the G7 would be an abdication of responsibility for any prime minister.”