The speaker of the US House of Representatives and the Republican president have not spoken directly for seven months but exchanged barbs this week as Congress and the White House work to respond to a coronavirus pandemic that has killed more than 91,000 people in the US.

"It's like a child who comes in with mud on their pants," Pelosi told a news conference on Wednesday when asked about provocative comments Trump has made about MSNBC television host Joe Scarborough, including references to him as "psycho."

"He comes in with doggy doo on his shoes and everybody who works with him has that on their shoes, too, for a very long time to come," Pelosi said, referring to canine excrement.

Trump, famous for his name-calling and insults, told reporters earlier in the week during a visit to Capitol Hill: "Pelosi is a sick woman. She's got a lot of problems. A lot of mental problems."

The president was responding to Pelosi's comments on Monday that he should not be taking the malaria drug hydroxychloroquine as a preventive medicine against the coronavirus because of his age and being in a weight group she said was "morbidly obese."

Pelosi, who is second in line for the presidency, has not spoken directly to Trump since October 16, when she attended a White House meeting on Syria.

Treasury Secretary Steven Mnuchin and other Trump administration officials led the negotiations with Pelosi and other congressional Democrats that resulted in $US3 trillion in coronavirus relief over the past two months.

Australian Associated Press