The former Chancellor’s two leadership rivals pulled out of the contest meaning Conservative members will not have their say.
Minutes before the nomination process closed at 2pm, Commons Leader Penny Mordaunt tweeted that she was withdrawing from the process, in apparent acknowledgment that she had failed to reach the threshold.
Ms Mordaunt said: “It is clear that colleagues feel we need certainty today. They have taken this decision in good faith for the good of the country.”
She added: “This decision is a historic one and shows, once again, the diversity and talent of our party. Rishi has my full support.”
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Former Prime Minister Boris Johnson discounted himself on Sunday evening stating that running “was not the right thing to do”.
Sir Graham Brady, chair of the 1922 Committee announced on Monday afternoon that there was only “one valid nomination” with the backing of 100 MPs, and declared: “Rishi Sunak is therefore elected as leader of the Conservative Party.”
Mr Sunak will formally take over from Liz Truss imminently after meeting with King Charles III, who will travel back to London from Sandringham later on Monday.
Many have shared their support for Mr Sunak, with former Prime Minister David Cameron tweeting: “Huge congratulations @RishiSunak on becoming PM to lead us through challenging times. I predicted a decade ago that @Conservatives would select our first Brit Indian PM & proud today that comes to be. I wish Rishi the v best, he has my wholehearted support.”
Scottish Conservative leader Douglas Ross said: “I’d like to congratulate Rishi Sunak on becoming the new Conservative Party leader and Prime Minister, and look forward to working with him for the good of Scotland and the whole United Kingdom.
However, others have been critical of Mr Sunak’s appointment, calling for a general election. Leader of the Liberal Democrats Sir Ed Davey claimed that the Tories have installed “another out-of-touch Prime Minister”.
He said: “The Conservative Party has trashed the British economy, pushed local health services to the brink, and added hundreds of pounds to people’s monthly mortgage payments. Now Conservative MPs have installed another out-of-touch Prime Minister with no plan to repair the damage and without giving the British people a say.
“Rishi Sunak has shown time and time again that he doesn’t understand the challenges facing struggling families and pensioners.”
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He continued: “We will now see more of the same, as Conservative MPs plot and squabble amongst themselves while completely ignoring the huge challenges facing the country. The only way to end the chaos is a General Election now.”
SNP Westminster Leader Ian Blackford said: “The Tories cannot be allowed to impose a third Prime Minister without a general election – voters must get a say and the SNP is determined to ensure they do.”
Mr Sunak is due to address MPs in the House of Commons on Monday afternoon.
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