U.K. Prime Minister Boris Johnson was moved to intensive care as his coronavirus symptoms worsened over the course of hours Monday, according to a statement from the government.

Foreign Secretary Dominic Raab will temporarily take over the prime minister’s duties while Johnson is hospitalized, the government said.

“Since Sunday evening, the Prime Minister has been under the care of doctors at St Thomas’ Hospital, in London, after being admitted with persistent symptoms of coronavirus,” a spokesman for No. 10 Downing Street said in a statement.

“Over the course of this afternoon, the condition of the Prime Minister has worsened and, on the advice of his medical team, he has been moved to the Intensive Care Unit at the hospital,” the spokesman said.

“The PM has asked Foreign Secretary Dominic Raab, who is the First Secretary of State, to deputise for him where necessary,” the spokesman added. “The PM is receiving excellent care, and thanks all NHS staff for their hard work and dedication.”

The Prime Minister is understood to be conscious and has been moved to the ICU at about 7pm as a precaution should he require ventilation to aid his recovery.

Johnson was conscious when he was transferred to the ICU around 7 p.m. GMT (3 p.m. ET). Johnson’s medical team made the decision to move him to that unit as a precaution in case he needed ventilation.

Johnson, 55, announced on March 27 that he had contracted the disease and was experiencing “mild symptoms,” including “a temperature and a persistent cough.”

Ten days later, Johnson entered a hospital “for some routine tests as I’m still experiencing coronavirus symptoms,” according to a tweet Monday morning from his official account.

“I’m in good spirits and keeping in touch with my team, as we work together to fight this virus and keep everyone safe,” Johnson said in the tweet.

Scotland’s First Minister Nicola Sturgeon tweeted: ‘My thoughts are with the PM and his family – sending him every good wish.’

Chancellor Rishi Sunak tweeted: ‘My thoughts tonight are with @BorisJohnson and @carriesymonds. I know he’ll be getting the best care possible and will come out of this even stronger.’

Business minister Nadim Zahawi tweeted: ‘Thoughts & prayers for @BorisJohnson & @carriesymonds and their family. I have known Boris for 20 years he is a fighter and will beat this virus.’

Labour leader Keir Starmer tweeted: ‘Terribly sad news. All the country’s thoughts are with the Prime Minister and his family during this incredibly difficult time.’

Members of the newly-formed shadow cabinet offered their support for the PM. Shadow justice secretary David Lammy tweeted: ‘Awful news. My very best wishes to the Prime Minister, as well as his partner Carrie, family and friends. Get well soon @BorisJohnson.”

Labour deputy leader Angela Rayner posted: ‘Sending my best wishes at this worrying time to the PM @BorisJohnson and @carriesymonds and hoping that his condition stabilises in his battle with #Coronavirus.’

And shadow deputy mental health minister Dr Rosena Allin-Khan tweeted: ‘I wish the Prime Minister a full and speedy recovery and thank the NHS team looking after him and everyone at St Thomas’.

Jeremy Corbyn said: ‘My thoughts are with Boris Johnson and his family tonight. Thanks to the NHS staff for their hard work and dedication.’

Mayor of London Sadiq Khan tweeted: ‘Praying for the Prime Minister’s swift recovery tonight. @GSTTnhs has some of the finest medical staff in the world, and he couldn’t be in safer hands.’