"We are United in our effort to defeat the Invisible China Virus, and many people say that it is Patriotic to wear a face mask when you can't socially distance," Trump wrote.

"There is nobody more Patriotic than me, your favorite President!"

We are United in our effort to defeat the Invisible China Virus, and many people say that it is Patriotic to wear a face mask when you can’t socially distance. There is nobody more Patriotic than me, your favorite President! pic.twitter.com/iQOd1whktN

— Donald J. Trump (@realDonaldTrump) July 20, 2020

The accompanying picture, in black and white, showed Trump wearing a dark mask with the presidential seal.

The stylish photo and exhortation for Americans to unite around masks was a far cry from Trump's longtime mocking of masks as symbols of weakness during a pandemic that he has repeatedly suggested is overblown.

However, his tweet stopped well short of endorsing calls from some for a nationwide mandate to wear masks in public.

The nation's top medical authorities -- backed by several leading Republican figures -- say that mask wearing is crucial to halting the disease.

Amid a fierce resurgence of the virus in southern and western states -- including some that are Republican strongholds -- Trump has come under new pressure to change his tune.

He only wore a mask in public for the first time on July 11. 

By contrast, his Democratic challenger in the November presidential election, Joe Biden, has worn a mask in public for months.