The president wrote in a tweet: “Get better soon Rudy, we will carry on!”

Mr. Giuliani, who has led the Trump campaign’s legal challenges to the election results, is the latest person close to the president to be infected.

The president and his team have been criticized for shunning safety guidance.

Recall that Donald Trump was ill in October.

Giuliani, 76, was admitted to the Medstar Georgetown University Hospital in Washington DC on Sunday, according to US media reports.

Following news of Mr. Giuliani’s diagnosis, the Arizona legislature announced sudden plans to shut down for one week. Several Republican lawmakers in the state had spent hours with the former New York mayor last week discussing election results.

In a tweet, Giuliani thanked well-wishers for their messages, and said he was “recovering quickly”.