Prime Minister Theresa May's office said May accepted the resignation on Monday and will announce a replacement soon. Will the resignations weaken or strengthen her hand? Many Brexit campaigners in her Conservative Party say she has betrayed her promise to pursue a clean break with the EU.
The man leading the UK's negotiating team, David Davis, resigned late on Sunday night, saying that he did not agree with the UK's proposals, so was the wrong person to be going into negotiations with them.
Theresa May only has a majority in Parliament with the support of the 10 MPs from Northern Ireland's Democratic Unionist Party, so any split raises questions about whether her plan could survive a Commons vote.
May's plan seeks to keep the United Kingdom and the European Union in a free-trade zone for goods, and commits Britain to maintaining the same rules as the bloc for goods and agricultural products.
Mr Johnson does not pull any punches, saying Brexit "should be about opportunity and hope" and a "chance to do things differently", but "that dream is dying, suffocated by needless self-doubt". European Council President Donald Tusk raised the idea that Brexit might be called off, writing on Twitter: "Politicians come and go but the problems they have created for people remain".
With less than nine months before Britain leaves and just over three before the European Union says it wants a deal, May has been forced to show her cards that she will commit the country to pursuing the closest possible trading ties with the EU.
Eight soccer team members rescued from flooded Thai cave, 5 remain trapped
Authorities on Monday confirmed that water inflows into the cave remained at controllable levels while drainage efforts continued. Authorities in northern Chiang Rai province began the unsafe mission to bring out the 12 boys and their coach earlier on Sunday.
A leadership challenge can be triggered if 15 per cent of members of parliament in May's Conservative Party write a letter to the chairman of the party's so-called "1922 committee".
"The decisions we take now will shape Britain's relationship with the European Union and the rest of the world for a generation".
Katie Bylis continued: 'As for the ongoing Brexit negotiations, it's now evens that no deal will be reached by the March 2019 deadline and if any other key players leave the Tory Party then those odds will shorten even further'.
Mr Davis, who has been Brexit Secretary since Mrs May became prime minister in 2016, said he had made compromises since taking on the role, but this was "one compromise too far". "It's imperative we do Brexit right, no half measures!" Did Theresa May clear the air or is the United Kingdom prime minister circling the wagons?
The value of the British pound dropped on global markets after Johnson's announcement, having risen after the announcement Friday that a Cabinet deal on Brexit had been agreed.