It will be the first time that Charles III appoints a head of government. The current tenant of Downing Street, Liz Truss, had been received by Elizabeth II on September 6 during an audience at the Scottish castle of Balmoral. The 96-year-old sovereign died two days later.
Liz Truss, who resigned on Thursday after just 44 days in office, will make her last speech outside 10 Downing Street around 10:15 a.m. (0915 GMT) and then travel to Buckingham Palace to tender her resignation to the King.
Rishi Sunak will then be received in audience by the king. He will finally go to Downing Street, where he will deliver a speech around 11:35 a.m. (10:35 GMT).
Former banker and Minister of Finance, Rishi Sunak will become, at 42, the youngest head of government in the contemporary history of the United Kingdom after a meteoric rise in politics. He is also the first of Indian origin and the first from a former British colony.
After his victory within his formation on Monday, he promised "stability and unity". "Bringing the party and the country together will be my top priority," he said in a brief address. "The UK is a great country, but there is no doubt that we face a profound economic challenge."
Rishi Sunak becomes the head of government of a country facing a serious economic and social crisis. Inflation exceeds 10%, the highest in the G7. Energy prices are soaring, as are food prices. The risk of recession hovers. He will also have to calm the markets, shaken by the Truss government's budget announcements at the end of September, all of which have since been canceled in disaster.
Rishi Sunak comes to power in a period of unprecedented instability: he is the fifth British Prime Minister since 2016, when the country chose in a referendum to leave the European Union. He is the third head of government in two months.
- Brexiter -
He took the lead of an extremely divided conservative party, after twelve years in power. On Monday, he told MPs they had to "unite or die", as the Labor opposition topped the polls two years ahead of the legislative elections.
Rishi Sunak ruled out early elections, demanded by Labour. But according to an Ipsos poll published on Monday, 62% of voters want an election before the end of 2022.
According to a YouGov poll, only 38% of Britons are happy that Rishi Sunak will become their Prime Minister.
This early Brexiter, who passes for a pragmatic worker, will have to form a government quickly, to both give guarantees to the markets and satisfy the clans of his majority, at the risk of suffering the same fate as Liz Truss. He will also have to explain his intentions: he did not speak during the Tories' lightning campaign which started on Thursday.
He won without a program or a vote from the members, after the renunciation of former Prime Minister Boris Johnson and the failure of his opponent Penny Mordaunt to qualify.
During the previous campaign last summer, when he was beaten by Liz Truss, this former Chancellor of the Exchequer (2020-2022) insisted on the need to fight inflation, calling the program his competitor, providing for significant tax cuts, a "fairy tale".
On immigration, he said he supported the ultra-controversial program of sending migrants who arrived illegally in the United Kingdom to Rwanda. However, this project is blocked in court.
As of Monday, the President of the European Council Charles Michel congratulated him and insisted on the need to restore "stability" in the United Kingdom.
Indian Prime Minister Narendra Modi also sent his "warmest congratulations" to his future British counterpart, welcoming the existence of this "living bridge" with his country that the Indians of the United Kingdom constitute, at a time when "we are transforming our historical ties into a modern partnership".