The former chancellor resigned from his ministerial post on Tuesday evening, just moments after Sajid Javid quit as health secretary.

It came as Mr Johnson faced further questions about his handling of the row over disgraced MP Chris Pincher, which ultimately led to him agreeing to step aside on Thursday.

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In his resignation letter to Mr Johnson, Mr Sunak said "the public rightly expect government to be conducted properly, competently and seriously", adding: "I believe these standards are worth fighting for and that is why I am resigning."

Announcing his bid, Mr Sunak said the country faces "huge challenges".

"Let's restore trust, rebuild the economy and reunite the country," he posted on social media.

In a video uploaded alongside his tweet pitching himself as the next Conservative leader, the former chancellor said: "Family is everything to me. And my family gave me opportunities they could only dream of.

"But it was Britain, our country, that gave them and millions like them the chance of a better future.

"I want to lead this country in the right direction.

"I ran the toughest department in government during the toughest times when we faced the nightmare of COVID.

"My values are non-negotiable: patriotism, fairness, hard work.

"We've had enough of division.

"Politics at its best is a unifying endeavour and I have spent my career bringing people together. Because that is the only way to succeed."

Numerous Conservative MPs were quick to endorse Mr Sunak as their preferred leadership candidate following his bid.

Conservative MP Mark Harper said the former chancellor has an "exciting vision for the future of the country".

He posted on social media: "I'm backing Rishi Sunak to restore trust, rebuild the economy, reunite the country, win the next election.

"I'm #ReadyforRishi as he represents a return to traditional Conservative values and has an exciting vision for the future of our country."

Fellow Conservative MP Angela Richardson, who quit her ministerial role as Michael Gove's parliamentary private secretary back in January citing "deep disappointment" with Mr Johnson's handling of the partygate scandal, also backed Mr Sunak for leader.

Former chief whip Mark Spencer was another to give his support to Mr Sunak.

"Rishi is the leader that can unite the party, bring the whole country together and win us that fifth general election victory.

"In serious times we need a person with a proven track record. Rishi gets my full support."

Red wall Tory MP Jacob Young also endorsed the former chancellor saying he has backed Teeside "time and time again".

"Rishi has the energy and vision to beat Labour in places like Redcar and I trust him to deliver for us with jobs, opportunities and a brighter future," he posted on social media.