Donald Trump said he was being "calm" like Winston Churchill in the Second World War when he "played down" coronavirus to the American public.
The US president recalled the famous slogan from a British wartime poster: "Keep Calm and Carry On."
It came as Mr Trump was under fire for having told journalist Bob Woodward that he publicly played down the potential impact of the virus in February and March, despite privately knowing how deadly it was.
Joe Biden has accused him of lying to the American people in an "almost criminal" way.
At a rally in Michigan on Thursday night he said: "As the British government advised the British people in the face of World War II, Keep Calm and Carry On. That's what I did.
"This whack job that wrote the book, he said, 'Well, Trump knew a little bit...'. They wanted me to come out and scream 'People are dying, we're dying'. No, no, we did it just the right way. We have to be calm, we don't want to be crazed lunatics. We have to lead."
He went on: "When Hitler was bombing, I don't know if you know this, when Hitler was bombing London, Churchill, great leader, would oftentimes go to a roof in London and speak.
"And he always spoke with calmness. He said we have to show calmness. No, we did it the right way and we've done a job like nobody."
Mr Trump has long been an admirer of Churchill. As soon as he arrived in the White House he returned a bust of the British prime minister to the Oval Office. Barack Obama had previously removed the bust.
Several thousand people attended Mr Trump's rally on Thursday night at an airport near Midland, Michigan.
Many supporters defied state guidelines and didn't wear masks, and there was little social distancing.
Mr Trump said: "This is not the crowd of a guy who comes in second place."
He went on to criticise Michigan's Democrat governor Gretchen Whitmer over coronavirus restrictions, saying she "doesn't have a clue" about reopening the state's economy. "Tell your governor to open up your state!" he said.
Michigan is an industrial state that along with Wisconsin and Pennsylvania helped propel Mr Trump to victory in 2016. He won it by just 10,704 votes.
Campaign officials said they are planning to spend "massive amounts" of time in Michigan before the election on November 3.
Mr Biden currently leads by four percentage points in the state, according to an average of recent polls.
The Democrat nominee visited Michigan on Wednesday, and hammered Mr Trump over the comments he made to Woodward.
Mr Trump accused Mr Biden of supporting trade deals that cost US jobs.
He said: "Joe Biden devoted his career to offshoring Michigan's jobs. Biden supported every disastrous globalist sellout for over a half a century."
Watch: Yahoo UK’s Health Editor, Alexander Thompson explain how coronavirus is treated