The British public will learn who the country’s new prime minister will be on Monday afternoon when the outcome of the Conservative Party leadership race is revealed.
The winner of the contest, widely expected to be Foreign Secretary Liz Truss, will be announced at 12.30pm UK time (3.30pm UAE time).
She has been competing against former chancellor of the exchequer Rishi Sunak.
UK Prime Minister Boris Johnson, who is expected to give his farewell speech on the steps of Downing Street tomorrow, will travel to Balmoral to tender his resignation to Queen Elizabeth II.
The new prime minister will travel to Scotland tomorrow to meet the queen and be formally asked to form a government.
The race between Ms Truss and Mr Sunak began when Mr Johnson announced his resignation in early July after support from his ministers and MPs collapsed.
A field of 11 candidates was whittled down to the final pair in a series of Tory MP ballots.
Mr Sunak initially had the most support from his fellow MPs, but Ms Truss proved to be more popular among the party's grassroots.
If she wins, Ms Truss, 47, will become the UK's third female prime minister, following Theresa May and Margaret Thatcher.
Ms Truss has been ahead of Mr Sunak, 42, in polling among the estimated 200,000 Tory members eligible to vote.
Postal and online voting closed on Friday after eight weeks of campaigning that Ms Truss described as "the longest job interview in history".
The new prime minister will take over amid a cost of living crisis, with soaring inflation, which is being driven mainly by rising energy prices.
Energy bills are set to rise to about £3,500 ($4,015) this winter for the average household, pushing many people into fuel poverty.
Ms Truss is said to be considering a freeze on energy bills for millions of households if she wins the contest.
Scottish Power has already put forward a £100 billion plan for a two-year energy bill freeze that will be financed by loans underwritten by the Treasury.
An energy company source said members of Ms Truss's campaign have “extremely actively explored” the idea, The Telegraph reported.
UK Business Secretary Kwasi Kwarteng, who has been tipped to become chancellor if Ms Truss wins, is reportedly “very open” to options for a freeze.
Another industry source said the proposal was being scrutinised by Ms Truss's campaign.
“I’m confident there will be a mechanism introduced that freezes bills," the source said.
Another source said the idea was discussed “quite a lot in the past fortnight".
A spokesman for the Truss campaign declined to comment.
On Sunday, Ms Truss said she would take “immediate action” on energy bills during her first week in office, but declined to give details.
She has also pledged to start cutting taxes from "day one" if named leader, including reversing April's increase in national insurance and next year's corporation tax increase from 19 per cent to 25 per cent.
The national insurance rise would mean the poorest people stand to gain about £7, while the wealthiest could gain about £2,000.
Ms Truss said the plan was fair, despite it benefiting higher earners.
"The people at the top of the income distribution pay more tax," she told the BBC's Sunday With Laura Kuenssberg programme.
"So inevitably when you cut taxes, you tend to benefit people who are more likely to pay tax. Of course, there are some people who don't pay tax at all.
"But to look at everything through the lens of redistribution I believe is wrong because what I am about is about growing the economy. And growing the economy benefits everybody."
Writing in the Financial Times on Monday, Mr Kwarteng tried to reassure markets by saying there would need to be “some fiscal loosening”, but that the new government would act in “a fiscally responsible way”.
“Liz is committed to a lean state and, as the immediate shock subsides, we will work to reduce the debt-to-GDP ratio over time," he said.
Ms Truss said she would would work tirelessly to make sure everyone has the “opportunity to go as far as their talent and hard work takes them”, The Sun reported.
“I have a bold plan to see Britain through difficult times and get us out the other side stronger. I won’t let anyone talk this great country down," she said.
“I will do everything in my power to make sure everyone, no matter where they are from, has the opportunity to go as far as their talent and hard work takes them.”
Everything you need to know about Liz Truss
What happens after leadership winner is announced?
The announcement by Conservative officials of who will take over as leader sets in motion a chain of events.
Mr Johnson will deliver a farewell speech before formally tendering his resignation to the queen, after which she will appoint his successor in a so-called kissing of hands ceremony.
For the first time in her reign, the 96-year-old monarch will appoint the prime minister at her Scottish retreat, Balmoral, rather than at Buckingham Palace in London.
The queen has suffered mobility problems and has cancelled several public engagements.
The next prime minister will be the 15th since the queen took the throne.
