Truss and her chancellor, Kwasi Kwarteng, announced large-scale tax cuts and borrowing in a mini-budget, which was widely criticised and largely reversed, having led to financial instability.

Following a change of rules by the 1922 Committee, each potential leader needed the support of at least 100 MPs to be a candidate in the vote, with a deadline of 2 pm on 24 October to secure enough nominations.

[3] Two candidates put their names forward: Penny Mordaunt, Leader of the House of Commons and Lord President of the Council, and Rishi Sunak, former Chancellor of the Exchequer.

In his victory speech, Sunak paid tribute to Truss and said that she "was not wrong" to want to implement growth and "admired her restlessness to create change", but admitted that "some mistakes were made" and promised to place economic stability and confidence at the heart of his government's agenda.

After having lost his working majority to defections and his own suspensions of rebel Members of Parliament, Johnson called a general election on a platform of completing the UK's withdrawal from the European Union.

[6] The government responded to the pandemic in March 2020 by enacting emergency powers and widespread societal measures including several lockdowns, and approved a vaccination programme which began in December 2020.

[11] The publishing of the Sue Gray report in May 2022 and a widespread sense of dissatisfaction led in June 2022 to a vote of confidence in his leadership among Conservative MPs, which he won.

[12][13] In late June 2022, the Conservative MP Chris Pincher resigned as deputy chief government whip after an allegation was made that he had sexually assaulted two men.

[21] During a hustings event, Truss suggested that it would be best to ignore the "attention seeker" Scottish First Minister Nicola Sturgeon before rejecting the possibility of a second independence referendum for Scotland.

[34][35][36] The policies of Trussonomics involve extensive tax cuts in addition to reducing government regulation and repealing employment laws to attract businesses, encourage entrepreneurship, and grow the economy.

The proponents' expectations were that, kick-started by a temporary scheme of lending, tax revenue would eventually increase due to growth in the economy, relieving the need for amassing debt from the tax-cutting measures.

[38] It led to a run on sterling, a fall in gilt markets, lost confidence among global investors and criticism from International Monetary Fund (IMF).

[38] Goldman Sachs, Bank of America and the IMF among others were sceptical that £45 billion unfunded tax cuts could lead to economic growth and pay for itself as the government hoped.

Conservative MP Mel Stride, a member of the Treasury Select Committee, wanted independent forecasts published to "provide reassurance and confidence to international markets and investors".

[50] Andrew Wishart, at Capital Economics, said the market reaction to Kwarteng's budget suggested mortgage rates of more than 6 per cent were now a "distinct possibility".

[52] On 27 September, the IMF also warned the UK government that it should re-evaluate the planned tax cuts announced in the mini-budget as they would heighten inequality and inflation in the country.

[55] In response, Truss and Kwarteng reversed the decision on the removal of the 45 pence of income tax for higher earners on 3 October following a significant backlash.

The International Monetary Fund (IMF), which acts to stabilise the global economy and sound economic warnings, took the unusual step of issuing a statement in which it openly criticised Truss's economic policies, stating that "the nature of the UK measures will likely increase inequality", and urging Truss's government to "re-evaluate" its tax measures, "especially those that benefit high income earners".

[72] According to The Telegraph, as of 17 October, there were at least five Conservative MPs calling for Truss's resignation: Crispin Blunt, Andrew Bridgen, Angela Richardson, Charles Walker and Jamie Wallis.

[82] Truss pledged as part of her leadership campaign to lift the moratorium on fracking, yet some Conservative MPs had expressed concern about the change as it went against their 2019 manifesto.

[84][85] As the day progressed, 10 Downing Street became increasingly concerned about the potential size of the rebellion among Conservative MPs and informed the climate minister, Graham Stuart, that the vote would no longer be treated as a matter of confidence.

Although he subsequently relayed this to the House of Commons, the whips' office were not made aware of the change, resulting in confusion and disarray among Conservative MPs.

[93][94] Labour MP Chris Bryant made claims on Sky News saying that he saw MPs "physically manhandled through the voting lobby" naming Deputy Prime Minister Thérèse Coffey along with Jacob Rees-Mogg as those he saw in the "group".

Later that evening, the Speaker of the House Lindsay Hoyle announced that he had asked the Serjeant at Arms and other parliamentary officials to investigate the allegations made about the incident.

"[106] US President Joe Biden thanked Truss "for her partnership on a range of issues including holding Russia accountable for its war against Ukraine".

[108] On 20 October, the online bookmaker Betfair listed Sunak as the favourite to become the new Conservative Party leader with odds of 11/10, with Mordaunt second at 7/2, Wallace third at 8/1, Hunt fourth at 9/1 and Johnson fifth at 13/1.

On the afternoon of the same day, Johnson spoke to Penny Mordaunt, with press speculation being that she had rejected an offer asking her to drop out of the leadership contest and back him.

In his victory speech, Sunak paid tribute to Truss and said that she "was not wrong" to want to implement growth and "admired her restlessness to create change", but admitted that "some mistakes were made" and promised to place economic stability and confidence at the heart of his government's agenda.

These changes, and the addition of an indicative vote by MPs between two final candidates, were introduced to narrow the field more quickly and reduce the probability that a ballot of party members would be required.

The following Conservative Party politicians were suggested by commentators as potential candidates for the leadership but declined to stand: Note: Some endorsements are repeated due to MPs changing support after withdrawal.