President Donald Trump on Saturday tweeted that the daily coronavirus task force briefings are "not worth the time and effort."

The president drew near-universal criticism on Thursday after suggesting that sunlight and consuming disinfectant could be effective coronavirus treatments.

At Friday's briefing, the president only spoke for 30 minutes, while on Saturday, no briefing was held.

Top Republicans are concerned that the president's erratic performances at the briefings may be behind recent polls showing declining support for the president in battleground states.

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President Donald Trump has tweeted that the daily White House coronavirus task force briefings are "not worth the time & effort," amid fears from top Republicans that his erratic appearances may be damaging his chances of reelection in November.

"What is the purpose of having White House News Conferences when the Lamestream Media asks nothing but hostile questions, & then refuses to report the truth or facts accurately. They get record ratings, & the American people get nothing but Fake News. Not worth the time & effort!" tweeted the president on Saturday night.

There was incredulity and near-universal criticism following the president's briefing on Thursday, when he floated the groundless and potentially dangerous idea that consuming disinfectant could be effective as a way of treating the virus.

On Saturday the briefing was cancelled, with aides reportedly increasingly concerned about evidence showing his chances of winning the presidential election are narrowing and his appearances at the briefing are a key factor.

Data in key battleground states such as Michigan and Pennsylvania shows Trump losing ground, reported The New York Times Saturday, and for some senior Republicans his comments on Thursday were a "breaking point."

On Friday, Trump only spoke for 30 minutes at the briefing and took no questions from the media, while on Saturday, the task force met privately and no briefing was held.

The president had insisted he was only being "sarcastic" when he suggested the treatments. On Saturday he lashed out at news reports that he had asked Dr Deborah Birx, the White House coronavirus task force coordinator, about the sunlight and disinfectant treatments at Thursday's briefing.

"Was just informed that the Fake News from the Thursday White House Press Conference had me speaking & asking questions of Dr. Deborah Birx. Wrong, I was speaking to our Laboratory expert, not Deborah, about sunlight etc. & the CoronaVirus. The Lamestream Media is corrupt & sick!" he tweeted.

Footage of the briefing recorded the following exchange:

Trump: "Deborah, have you heard of that? The heat and the light, relative to certain viruses, yes, but relative to this virus?"

Birx: "Not as a treatment."