By Joshua Nevett
BBC Politics
Rishi Sunak, who volition go the adjacent UK premier curate wrong hours, has issued a plea for unity successful the look of a "profound economical challenge".
He won the Tory enactment contention aft rival Penny Mordaunt failed to unafraid capable backing from MPs.
In his archetypal speech, Mr Sunak said bringing his enactment and the UK unneurotic would beryllium his "utmost priority".
Mr Sunak, 42, volition beryllium the UK's archetypal British Asian premier curate and the youngest for much than 200 years.
Mr Sunak - a practising Hindu - is expected to instrumentality bureau aboriginal this greeting aft being formally appointed by the King.
After chairing her last furniture gathering astatine 09:00 BST, the outgoing premier curate volition marque a connection extracurricular No 10 earlier travelling to Buckingham Palace for her last assemblage with the King.
This volition beryllium followed by Mr Sunak's archetypal assemblage with the monarch, during which helium volition beryllium invited to signifier a government.
He volition past question to Downing Street to marque a connection astatine astir 11:35, earlier entering No 10.
President Joe Biden has said helium plans to telephone Mr Sunak to "offer his congratulations" aft his gathering with the King, the White House Press Secretary said.
Mr Sunak takes bureau arsenic the 3rd Conservative premier curate since the enactment won the past wide predetermination successful 2019 - prompting Labour to pb calls for an aboriginal wide predetermination arsenic a result.
In his code connected Monday - which took spot down closed doors - Mr Sunak told them this was going to beryllium a pugnacious play and ruled retired an aboriginal wide election, MP Simon Hoare said.
The erstwhile chancellor said the Conservative Party, trailing Labour successful the polls by immense margins, was facing an "existential threat", but could triumph the adjacent predetermination by uniting.
Three MPs successful the country told PA Media quality bureau Mr Sunak's connection to the enactment was "unite oregon die", arsenic they absorption connected delivering connected the public's priorities during a outgo of surviving crisis.
Later, successful a TV code that lasted little than 2 minutes, Mr Sunak promised to service with "integrity" and thanked outgoing Prime Minister Liz Truss for starring the state during "exceptionally hard circumstances".
"The United Kingdom is simply a large state but determination is nary uncertainty we look a profound economical challenge," helium said. "We present request stableness and unity and I volition marque it my utmost precedence to bring our enactment and our state together."
Mr Sunak's coronation, successful effect, arsenic Tory person caps a accelerated governmental comeback by the erstwhile chancellor aft helium mislaid retired to Ms Truss successful the past enactment contention during the summer.
Ms Truss - whose tax-cutting docket Mr Sunak dismissed arsenic "fairytale economics" - tweeted to congratulate him and connection her "full support".
Her successor volition instrumentality bureau astatine a clip of economical situation and unit connected nationalist finances, exacerbated by Ms Truss's mini-budget, astir of which has been scrapped.
Conservative Party Chairman Jake Berry said it was clip for the enactment to "unite four-square down Rishi" aft a play of aggravated governmental turmoil nether Ms Truss's premiership.
Mr Sunak's enactment rival Penny Mordaunt withdrew from the latest contention minutes earlier the effect was announced, admitting it was "clear that colleagues consciousness we request certainty today".
"This determination is an historical 1 and shows, erstwhile again, the diverseness and endowment of our party," Ms Mordaunt said. "Rishi has my afloat support."
Ms Mordaunt took the enactment contention to the wire, but came nether unit to unite down Mr Sunak aft erstwhile Prime Minister Boris Johnson withdrew from the contention connected Sunday.
Mr Johnson - who resigned arsenic premier curate lone 7 weeks agone - claimed helium had capable enactment to basal but acknowledged present was "not the close time".
Sources told the BBC that Mr Sunak and Mr Johnson met connected Saturday arsenic Tory MPs decided who to backmost successful the 2nd Tory enactment contention successful 4 months.
Mr Sunak was chancellor successful Mr Johnson's authorities and wrong weeks of taking the relation had to steer the UK system done the Covid-19 pandemic.
But helium discontinue arsenic chancellor successful July aft the authorities was dogged by scandals, giving momentum to a furniture mutiny that forced Mr Johnson from office.
First elected arsenic an MP for the constituency of Richmond successful North Yorkshire successful 2015, Mr Sunak has experienced a meteoric emergence to the apex of British politics.
Before becoming an MP, Mr Sunak worked successful concern and is thought to beryllium 1 of the richest MPs.
But his family's finances came nether aggravated scrutiny earlier this year, erstwhile the taxation affairs of his wife, Akshata Murty, were placed successful the spotlight.
Rishi Sunak: The basics
Place of birth: Southampton
Home: London and Yorkshire
Education: Winchester College, Oxford University, Stanford University
Family: Married to businesswoman Akshata Murty with 2 daughters
Parliamentary constituency: Richmond (Yorkshire)
Opposition parties person been clamouring for a wide election, arguing that Mr Sunak does not person a antiauthoritarian mandate to go premier minister.
Mr Sunak volition beryllium the 4th consecutive premier curate - aft Theresa May, Mr Johnson and Ms Truss - to instrumentality the relation of person without a wide election, though Mrs May and Mr Johnson some won wide elections arsenic PMs successful 2017 and 2019.
The adjacent wide predetermination is not owed to instrumentality spot until January 2025 at the latest, aft the Conservatives won a landslide bulk successful 2019.
Mr Sunak is nether nary work to telephone an aboriginal predetermination nether the UK's parliamentary governmental system.
Labour's lawman person Angela Rayner said Mr Sunak had been crowned premier curate "without him saying a azygous connection astir however helium would tally the state and without anyone having the accidental to vote".
Liberal Democrat person Ed Davey said Tory MPs had "installed different out-of-touch premier curate with nary program to repair the harm and without giving the British radical a say".
Scotland's First Minister Nicola Sturgeon said Mr Sunak should telephone an aboriginal wide predetermination and indispensable not "unleash different circular of austerity".