Behind the scenes, European Union member states are fearful a collapse of Britain's minority Conservative Government would spell the end for Brexit negotiations and lead to a no deal.
Dominic Raab, a Brexit supporter and former housing minister, was appointed to replace Davis only days before negotiations in Brussels are due to resume next week.
On Monday, high-profile Brexiteer and Conservative MP Johnson announced he was resigning from the Cabinet, following the agreement of a Brexit proposal that would see the United Kingdom retain close links to the European Union after exiting the organisation.
This tweet summed the whole thing up pretty well.
"This afternoon, the Prime Minister accepted the resignation of Boris Johnson as Foreign Secretary", a statement from Downing Street said.
Mrs May said she was "sorry - and a little surprised" by Mr Johnson's move after his apparent support on Friday.
Mrs May was forced to carry out a reshuffle of her top team after Boris Johnson and David Davis both quit.
It didn't take long for someone to get a Harry Potter reference in there, either.
When asked whether May would contest any vote on a confidence motion in her leadership, her spokesman said: "Yes".
The campaign is fighting to give the public the final say on Brexit, a deal that is "too big to be ignored by the people".
Johnson's departure came a day after David Davis, the British minister in charge of Brexit negotiations, also stepped down in protest of May's new Brexit strategy that pointed to a more "business-friendly" deal with the EU.
"It is as though we are sending our vanguard into battle with the white flags fluttering above them", Johnson wrote in a letter that underscored his credentials as a champion of full-speed Brexit.
In response to questions about whether the government is in "meltdown", May's spokesman said "it is not".
To me, it looks like the buyers are buying the Brexit dips in anticipation of a rate hike and better economic news. But leading pro-Brexit lawmaker Jacob Rees-Mogg said he did not think she would face a leadership challenge.
May said the plan would deliver frictionless trade with Europe and was the "only way to avoid a hard border" between the U.K.'s Northern Ireland and European Union member Ireland. He said that if Parliament was deadlocked, Britain might need to hold another referendum on leaving the EU. They also argued that the proposals breach several of the "red lines" the government had set out, including a commitment to leave the EU's tariff-free customs union.