With British Prime Minister Boris Johnson fighting for health in the intensive case of a hospital in London, the UK is facing a leadership crisis.

The 55-year-old prime minister was taken to the hospital on Sunday night for routine tests after struggling to shake off Covid-19, but his condition worsened during Monday afternoon.

Britain has no formal succession plan should the prime minister become incapacitated, but Johnson, 55, has asked Foreign Secretary Dominic Raab to deputise for him.

Raab is a former Foreign Office lawyer who has been both an ally and a rival to his boss.

During the Brexit campaign in 2016, Raab campaigned alongside Johnson successfully to break away from the European Union. Three years later, the pair stood against each other in the Conservative Party’s leadership contest.

Raab, who was the Brexit minister under former premier Theresa May, quit after just three months in November 2018 in protest at May’s doomed divorce deal with Brussels that he said offered too many concessions.

But when Johnson became Conservative party leader and prime minister after May’s resignation in July last year, Raab was catapulted back into government.

His role as foreign secretary also carries the title first secretary of state, implying seniority over all other ministers except the prime minister and making him his de facto deputy.

Often combative, he holds a black belt in karate and is a keen boxer.

His Czech-born Jewish father came to Britain in 1938 as a six-year-old refugee. He died of cancer when Raab was 12 and his mother brought him up in the Church of England.

He competed in karate for 17 years, making the UK squad.

After studies, he became an international lawyer at London legal firm Linklaters before joining the Foreign Office in 2000 as an advisor.

Raab was posted to The Hague in 2003 to head a team focused on bringing justice to war criminals including Slobodan Milosevic, Radovan Karadzic and Charles Taylor.

From 2006 to 2008, he was chief of staff to the Conservatives’ home affairs spokesman David Davis while in opposition.