Dominic Raab will take the charge of the UK government if Prime Minister Boris Johnson is struck down by coronavirus, according to an announcement made by Downing Street as "designated survivor" plans on Monday.
In the Johnson cabinet, Raab is the foreign secretary as well as the first secretary of state, which makes him next in line in a situation in which the prime minister is unable to carry out his duties
Downing Street stressed that the prime minister is "well", but when asked who would take charge if he became incapacitated, replied: "The foreign secretary is the first secretary of state."
The clarification comes after reports that some ministers have been pushing for Michael Gove, the cabinet office minister and key Johnson ally, to take over if necessary – rather than Mr Raab, independent.co.uk reported.
The prime minister – unlike Donald Trump – is not believed to have been tested for coronavirus, but is thought to be at higher risk because of regular, intense meetings to combat the crisis.
The announcement came in the context of growing numbers of deaths and cases, with London accounting for 2,200 (117 in Westminster) of the nearly 5,700 cases across the country.
Westminster has been identified as a virus hotspot, with several dozen MPs now in isolation and expectations that parliament will soon be shut down.
Mr Raab, Mr Gove, the chancellor Rishi Sunak, and Matt Hancock, the health secretary, each chair a committee coordinating different parts of the government's response.
Successive prime ministers have resisted pressure to set out a formal procedure for what happens if someone else is required to take over.
Peter Bone, a Conservative backbencher, has tried to pass a law without success and said, on Sunday: "Nobody seems to be able to tell me what happens if the prime minister is incapacitated.
"In a national emergency, you don't want to be scrabbling around worrying about who's in charge. And you don't want the foreign secretary and the cabinet office minister arguing about who's in charge."
As the crisis escalates, Downing Street has been forced to play down reported tensions between Mr Gove and Mr Hancock, who is leading the NHS response.
Mr Raab has, so far, been the face of efforts to help up to a million Britons stranded abroad, facing criticism for insisting it is impossible for the government to lay on repatriation flights.
He also came under fire for claiming the pandemic strengthened the case for completing Brexit at the end of the year – even as an extended transition period appears increasingly inevitable.
The prime minister's spokesperson declined to set out any further detail of the "designated survivor" plans, but stressed the flexibility available to him.
"The prime minister has the power to delegate responsibility to any of his ministers but, for now, it's the prime minister and then the foreign secretary," he said.
Johnson, meanwhile, put Britain in a lockdown as he announced sweeping curbs on everyday activity including the banning of any gatherings of more than two people who do not live together.
As well as instructing the public to "stay at home" for all but a few exceptions, Johnson said he was ordering shops that don't sell essential goods, such as food and medicines, to close immediately.
In as somber an address to the nation as any prime minister has arguably delivered since World War II, Johnson said it was critical to prevent the virus from spreading between households and that police would be authorized to break up gatherings of more than two people from different households in public in order to deal with the "biggest threat this country has faced for decades".
Under the measures which Johnson did not term as a lockdown, people will only be allowed to leave home for a few "very limited purposes" to relieve the pressure on the National Health Service, Johnson said.
These include shopping for basic necessities "as infrequently as possible," one form of exercise a day done alone or with household members, medical reasons or travelling to work that cannot be done from home or that is "absolutely necessary."