By Holly Ellyatt

Boris Johnson has won a Conservative Party leadership race and will become the U.K.’s next prime minister.

Johnson was elected as his party leader, and consequently the U.K. leader, only by the estimated 160,000 members of the ruling Conservative Party. He will take up office on Wednesday.

The new prime minister, who has previously been the U.K. foreign minister and mayor of London, will likely usher in a new team of ministers. Some incumbents have already announced their impending departure, including Finance Minister Philip Hammond, largely because of their different stances over Brexit.

The leadership contest took place after Theresa May announced she would resign as prime minister following repeated rejections of the Brexit deal she struck with the EU last year.

How Johnson will proceed with Brexit now will be an immediate focus, given an impending deadline to leave the bloc of October 31, and still no deal agreed upon by the U.K. parliament.

Johnson is infamous for his off-the-cuff remarks and somewhat eccentric character, and he has long been an influential and outspoken member of the Conservative Party. His decision to support the “Leave” vote ahead of the U.K.’s referendum on EU membership in June 2016 was seen as having a decisive effect on the result.

Since then, Johnson has made more controversial remarks over Brexit; most recently insisting that the U.K. must leave the EU on October 31 “do or die, come what may” despite widespread concern over what a “no-deal” departure could mean for U.K. businesses and the economy.

Leaving without a deal in place with the EU would mean there is no transition period for the country to get used to life outside the EU’s trading bloc. Trade and transport links between the EU and U.K. could therefore be severely affected.

Johnson also got into hot water in recent weeks for his apparent reluctance to support the U.K.’s ambassador to the U.S. following a leak of secret memos criticizing the President Donald Trump administration.

This is a breaking news story, please check back later for updates.

This article first appeared on CNBC and is republished with its permission.