Boris Johnson, one of the leading voices in the Brexit campaign and the man considered to be the favorite to replace outgoing Prime Minister David Cameron, delivered a bombshell Thursday, June 30 when he announced he didn't want the job, CNN reports.

Living up to his reputation as a political maverick, the former London mayor outlined the demands of the role over the course of a lengthy speech in London and then said: "Having consulted colleagues and in view of the circumstances in Parliament, I have concluded that that person cannot be me."

The charismatic Conservative MP played a decisive role in the campaign to lead Britain out of the European Union -- an endeavor many saw as partly an effort to position himself as the future leader of the ruling Conservative Party, and of the country.

The announcement drew a stunned response across the UK and beyond. On social media, it was met with disbelief and anger, CNN says.

Since the unexpected Leave vote sent the pound tumbling, hurt global markets and inspired renewed talk of Scottish independence, many have seen Britain as a casualty of Johnson's now-thwarted leadership ambitions.

Johnson's decision means that five Conservative MPs will compete to replace Cameron, who announced his intention to resign after narrowly losing his campaign to persuade voters to remain in the EU in the national referendum last week.

They include three Cabinet ministers: Gove, Home Secretary Theresa May and Work and Pensions Secretary Stephen Crabb. Former defense secretary Liam Fox and Energy Minister Andrea Leadsom are also running, CNN says.