Donald Trump clashed with a reporter during a White House news conference after demanding he remove his mask to ask a question.
The US president never wears a mask in his frequent media briefings, but many of the watching reporters do - in accordance with the US Centres for Disease Control guidelines to don a face covering.
But on Monday, as Reuters reporter Jeff Mason began asking him a question, Mr Trump interjected: "You’re going to have to take that off please.”
The journalist raised his voice - clearly audible - and tried to continue, but the US leader grew frustrated, insisting: “You can take it off. How many feet are you away?”
Mr Mason said he would instead speak louder, prompting the president to fire back: "Well, if you don't take it off you're very muffled, so if you would take it off, it would be a lot easier."
However, Mr Mason refused and raised his voice instead, asking: "Is that better?"
Mr Trump rolled his eyes and let out a loud sigh as he answered: "It’s better, yeah.”
It is not the first time the pair have clashed over face masks. During a lively exchange in May, Mr Trump told Mr Mason, “you want to be politically correct” when he refused to remove his mask to ask a question.
"No. I just want to wear the mask," Mr Mason shot back, his mask in place.
The president frequently asks reporters to remove their masks during briefings, and some comply.
Mr Trump was pictured in public donning a mask for the first time in mid-July during a visit to Walter Reed National Military Medical Center in Bethesda, Maryland.
He insisted at the time that he had “never been against masks”, but in April he said: "I don't think I'm going to be doing it. Wearing a face mask as I greet presidents, prime ministers, dictators, kings, queens - I just don't see it."
The Republican has also mocked his Democrat rival Joe Biden for “liking” masks too much, as the pair enter the final two months of the presidential race ahead of election day on November 3.
During Monday’s press conference, Mr Trump accused his rivals of "disparaging" for political gain a vaccine he has said could be available before polling day.
He told the White House briefing: "It's so dangerous for our country, what they say, but the vaccine will be very safe and very effective."
Mr Trump levelled the accusation a day after Senator Kamala Harris, the Democrats' vice presidential candidate, said she "would not trust his word" on getting the vaccine.
"I would trust the word of public health experts and scientists, but not Donald Trump," Ms Harris said, amplified by Mr Biden.