New Covid cases in the US topped 89,000 for the first time in the largest single-day tally since the start of the pandemic.
The latest record is over 6,200 cases higher than the previous high of 83,734 recorded on Saturday, according to figures kept by The Washington Post.
With the record-setting numbers, the country's total infections are expected to pass nine million by Friday, while the death toll has risen to at least 228,000.
The case increases were driven by surges in Midwest states including Illinois, Ohio, and Iowa, with South Dakota, Wyoming, Idaho, Oklahoma and Wisconsin seeing new highs in reported deaths, according to the figures.
Speaking in Florida on Thursday, Joe Biden said that 160,000 lives could have been saved if the Trump administration had acted sooner and coordinated a more effective pandemic response.
Donald Trump, meanwhile, has maintained the country is "rounding the corner".
Dr Anthony Fauci, the White House's infectious disease expert, said on Wednesday that the increasing number of cases were due to the varied reopening responses of the states.
"It was like a free-for-all," Dr Fauci said.
Dr Irwin Redlener, of the National Center for Disaster Preparedness at Columbia University, said the inconsistency of the government's response has been frustrating efforts to control the spread.
“If we had just been disciplined about employing all these public health methods early and aggressively, we would not be in the situation we are in now,” Dr Redlener told the Associated Press.
Estimating that 130,000 deaths could have been avoided if the country embraced masks and social distancing, Dr Redlener questioned how Mr Trump “didn’t understand how many people followed his advice” and said the president has “blood on his hands.”