It lost its working majority on 3 September 2019 when Tory MP Phillip Lee crossed the floor to the Liberal Democrats.

Theresa May announced on 24 May 2019 that she would resign as Leader of the Conservative Party and therefore prime minister, after failing three times to secure passage through the House of Commons of her Withdrawal Agreement and Implementation Bill, which would have seen the United Kingdom leave the European Union.

Johnson inherited a minority government, supported by a confidence and supply agreement with the Democratic Unionist Party of Northern Ireland.

[3] Johnson also created a new ministerial title to be held by himself, Minister for the Union, fulfilling a campaign pledge he had made in the leadership election.

[12] On 5 September 2019, Johnson's brother and Orpington MP Jo Johnson announced his intention to resign both his ministerial position and parliamentary seat, stating "In recent weeks I've been torn between family loyalty and the national interest — it's an unresolvable tension & time for others to take on my roles as MP & Minister.

"[13] On 7 September 2019, Amber Rudd announced she was resigning as Secretary of State for Work and Pensions and Minister for Women and Equalities, and leaving the Conservative Party.