The White House coronavirus task force has warned much of the United States is in the grip of an unrelenting rise in cases and urged tough countermeasures.
At least nine US states reported record daily increases in new infections on Thursday.
The hardest-hit west and midwest regions encompass a number of battleground states expected to play a pivotal role in Tuesday's presidential election.
"We are on a very difficult trajectory. We're going in the wrong direction," said leading task force member and National Institute of Allergy and Infectious Diseases director Anthony Fauci.
The nation's top infectious disease expert says virus cases are on the rise in 47 states and patients are overwhelming hospitals across the country.
"If things do not change, if they continue on the course we're on, there's gonna be a whole lot of pain in this country with regard to additional cases and hospitalisations and deaths," Fauci told CNBC on Wednesday night.
The White House coronavirus task force has warned states in the middle and western parts of the country aggressive measures will be necessary to curb the spread, according to weekly state reports seen by CNN.
"We continue to see unrelenting broad community spread in the midwest, upper midwest and west. This will require aggressive mitigation to control both the silent asymptomatic and symptomatic spread," one said.
The ominous assessment was echoed on Thursday by Brown University dean of public health Dr Ashish Jha, who said "things are very, very bad in the United States right now".
"We are having some of the largest breakouts we've had during the entire pandemic," he said, adding that the initial waves of infections last spring were more localised.
"And nine, 10 months into this pandemic, we are still largely not quite prepared."
At least nine states - Indiana, Ohio, Maine, Minnesota, Illinois, North Dakota, North Carolina, Michigan and Oregon - reported record one-day increases in COVID-19 cases on Thursday.
Indiana also reported a record number of hospitalisations, which are soaring across the country, a metric independent of how much testing is being done.
As of Thursday, there were 45,457 COVID-19 patients in US hospitals, the highest number since August 14.
Nearly 228,000 people have died of the respiratory virus in the United States since the outbreak began - the world's highest national toll - and 8.6 million infections have been documented to date.
Ohio Governor Mike DeWine announced the creation of "COVID Defense Teams" of community leaders to focus on measures for slowing the spread.
"The virus is raging throughout the state, and there is no place to hide," DeWine told a news conference as he urged residents to become more diligent in wearing masks, social distancing and hand-washing.
Health experts believe the virus is surging because of more private social gatherings, colder temperatures driving people indoors and Americans' letting their guard down due to fatigue with restrictions.
Fauci says the first doses of a coronavirus vaccine might become available to some high-risk Americans in late December or early January, if all goes well.
On the campaign trail, President Donald Trump has repeatedly downplayed the virus, claiming for weeks that the country is "rounding the turn".