Massachusetts US Army National Guard soldiers distribute food at John Ruiz Park to people suffering from food insecurity due to the coronavirus (COVID-19) pandemic in Chelsea, Massachusetts on May 11, 2020. [Photo/Agencies]

As the number of novel coronavirus cases has hit record highs in 12 US states, the pandemic also has become more politicized, with US President Donald Trump attributing the rise to increased testing, and the governors of two major states feuding.

Trump said the United States has tested 25 million people, far more than other countries.

"When you do testing to that extent, you're going to find more people, you're going to find more cases. So I said to my people slow the testing down, please," Trump told a campaign rally in Tulsa, Oklahoma, on Saturday.

"The President's efforts to slow down desperately needed testing to hide the true extent of the virus mean more Americans will lose their lives," House Speaker Nancy Pelosi said in a statement Sunday.

A White House official later said Trump's call for a testing slowdown was in jest.

Peter Navarro, the White House director of trade and manufacturing policy, said Sunday that the administration was preparing for the possibility of a second wave of the virus in the fall.

"We are filling the stockpile in anticipation of a possible problem in the fall," Navarro told Jake Tapper on CNN's State of the Union.

Scott Gottlieb, former Food and Drug Administration commissioner, said Sunday that outbreaks in several states, including Texas, Florida and Arizona, could overwhelm hospital systems if not properly managed.

"We're seeing a resurgence in the South and the Southeast; they really never got rid of their epidemics," Gottlieb said on CBS' Face the Nation. "A challenge that was once facing some regions of the country is now facing every region of the country, and the worry is they're going to tip into exponential growth.

"We know that there's community spread underway now in states like Florida, Texas, California, for that matter, and Arizona," he said. "Those are big states that have a lot of cases that have been building."

Dr Michael Osterholm, director for the Center of Infectious Research and Policy at the University of Minnesota, speaking on NBC's Meet the Press, compared the virus to a "forest fire".

"I don't think this is going to slow down. I'm not sure the influenza analogy applies anymore," he said. "I think that wherever there's wood to burn, this fire is going to burn it."

Cases are rising in 18 states across the South, West and Midwest. Nationally, the US has nearly 2.3 million coronavirus cases, with close to 120,000 deaths, according to Reuters.

Eleven states on Sunday reported new highs in their seven-day averages, with Oklahoma reporting the largest at 16 percent. Florida reported more than 4,000 new cases on Saturday, bringing its total to about 97,000 cases, with more than 3,000 deaths, according to Reuters.

California, Texas, Alabama, Oklahoma and Oregon reported record numbers last week, too.

Although cases have risen, the number of COVID-19 fatalities has plunged. The 14-day average was down more than 40 percent as of Saturday, The New York Times reported.

Governor Ron DeSantis of Florida, a Republican, said that more younger people, in their 20s and 30s, are testing positive in the state.

But he also took a swipe at the coronavirus response by New York's Democratic Governor Andrew Cuomo, who last week suggested that the Empire State may quarantine visitors from Florida.

"I would just ask if that's done, just please do not quarantine any Floridians in the nursing homes in New York," DeSantis said Saturday at a news conference in Tallahassee.

Cuomo has faced criticism for virus-related deaths among the elderly after state health officials in March ordered nursing homes and rehabilitation centers to admit COVID-19 patients who were discharged from hospitals. The order was later rescinded.

New York has recorded more than 392,000 coronavirus infections, and nearly 31,000 deaths.

Amid New York's crisis, DeSantis said that New Yorkers heading to Florida were required to self-quarantine for two weeks upon arrival.

On Thursday, Cuomo said a quarantine on travelers from Florida to New York was "something I'm considering".

It is Florida where the president is expected to deliver his acceptance speech at the Republican National Convention on Aug 27 in Jacksonville, at an arena with a capacity of 15,000.

China said Sunday that it has suspended poultry imports from a Tyson Foods facility where hundreds of workers have tested positive for the coronavirus.

China's General Administration of Customs office announced the suspension Sunday in a news release noting the company "recently occurred employees with new pneumonia aggregation infection".

Tyson Foods on Sunday confirmed that the facility was in Springdale, Arkansas.

Reuters contributed to this story.