EXCLUSIVE: House Republican Whip Steve Scalise and the top Republican on the House Oversight Committee James Comer are demanding House Democrats launch a "full and complete" investigation of China’s alleged role in the origins of COVID-19. 

House Republicans say they have been calling on Democrats on the Select Subcommittee on the Coronavirus Crisis and the Committee on Oversight and Reform to "hold the Chinese Communist Party accountable for its role in causing the global COVID-19 pandemic" since last year. 

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"In light of new evidence, and your ongoing refusal to acknowledge legitimate questions related to the CCP, we are writing to renew our long-standing request for a full investigation of China’s liability," Scalise and Comer wrote in a letter to Subcommittee on the Coronavirus Crisis Chair James Clyburn and House Oversight Committee Chair Carolyn Maloney. 

Scalise and Comer, in their letter to Clyburn and Maloney, first obtained by Fox News, said they shared "evidence that the CCP obscured the virus’ origins, manipulated the World Health Organization to cover up the severity of the initial outbreak, and leveraged the crisis to steal American medical research, among other things." 

WASHINGTON, DC - APRIL 20: Rep. Steve Scalise (R-LA) speaks during a press conference following a House Republican caucus meeting on Capitol Hill on April 20, 2021 in Washington, DC. The House Republican members spoke about the Biden administration's immigration policies and the coronavirus pandemic. (Photo by Sarah Silbiger/Getty Images)

WASHINGTON, DC - APRIL 20: Rep. Steve Scalise (R-LA) speaks during a press conference following a House Republican caucus meeting on Capitol Hill on April 20, 2021 in Washington, DC. The House Republican members spoke about the Biden administration's immigration policies and the coronavirus pandemic. (Photo by Sarah Silbiger/Getty Images) (Getty Images)

"Repeatedly, we called for a full investigation to address those questions. Repeatedly, you ignored our requests," they wrote, noting that Republicans in the House have been urging House Democrats to "bring investigative resources to bear on questions" related to China and COVID-19. 

Scalise and Comer said there is "extensive evidence that the CCP denied and downplayed the severity of the COVID-19 outbreak, and exploited the pandemic to gain a strategic advantage." 

But Scalise and Comer said the matter "is more urgent" in light of a Wall Street Journal report over the weekend that three researchers from China’s Wuhan Institute of Virology became ill and sought hospital care in November 2019. The report cited a previously undisclosed U.S. intelligence document. 

"In short, there is evidence the CCP started the pandemic, covered it up, and is responsible for the deaths of almost 600,000 Americans and millions more worldwide," they wrote. "These questions are not a diversion as Speaker Pelosi has stated—they get to truth and accountability. 

"The House Democrat majority’s refusal to follow the science, listen to the experts, and investigate the origins of COVID-19 raises serious questions about the credibility of the Select Subcommittee because we are uniquely positioned to find the truth, and seeking those answers is squarely within our mandated jurisdiction," they continued, adding that investigating the origins of COVID-19 "is clearly within the scope" of the subcommittee’s jurisdiction." 

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"Even President Biden and others in the Biden Administration are now expressing the need for a full investigation into the CCP’s actions," they added. 

Scalise and Comer went on to quote top Biden Administration officials, like Health and Human Services Secretary Xavier Becerra, Dr. Anthony Fauci, Secretary of State Antony Blinken and Director of National Intelligence Avril Haines, and their calls for an "impartial" investigation. 

The officials all had expressed concern with a report released last month by the World Health Organization and China that dismissed claims that COVID-19 had escaped from the lab in Wuhan, calling the theory of zoonotic transmission, or transfer of infection from animals to humans, "likely to very likely."

The report called the prospect that the virus transmitted from an animal reservoir to an animal host, followed by subsequent spread within that intermediate host that then transmits it to humans, "likely to very likely." It also said the idea that the virus may have leaked from the Wuhan Institute of Virology "extremely unlikely."

The report called for further investigation in every area except the lab leak hypothesis.

At the time of its release, Biden officials said the report lacked crucial information and provided just a "partial, incomplete picture" of the virus' origin, while White House press secretary Jen Psaki said the report did not "meet the moment," while calling for "unfettered access" to data from China and the WHO. 

Even WHO Director-General Tedros Adhanom Ghebreyesus at the time said the research team’s assessment on whether coronavirus entered the human population as a result of a laboratory incident was not "extensive enough."

Scalise and Comer, though, slammed Democrats in the House, saying they "appear intended to advance a political narrative at the expense of accountability for the CCP." 

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"We hope you will abandon this partisan agenda and join our investigation into the origins of COVID-19," they wrote. "This is one of the most important questions that demands answers." 

On Monday, the White House again called for a "transparent" international investigation into the origins of COVID-19, and said it is committed to getting answers through an "expert-driven evaluation of the pandemic's origins that is free from interference or politicization." 

Psaki referenced the "phase one" results of the World Health Organization's investigation into the origins of COVID-19, saying the White House did not have "access to data." 

"Now we're hopeful that we can move into a more transparent, independent Phase two investigation," Psaki said, again calling for "access to the underlying data and information." 

"An international investigation led by the World Health Organization is something that we've actually been pressing for, for several months, in coordination with a range of partners around the world," Psaki continued. "We need that data. We need that information from the Chinese government. What we can't do, and what I would caution anyone from doing, is leaping ahead of an actual international process." 

She added: "We don't have enough data and information to jump to a conclusion at this point in time."

Meanwhile, last week, Republicans on the House Intelligence Committee said there is "significant circumstantial evidence" that the COVID-19 outbreak stemmed from a leak at the Wuhan lab and are urging the federal government to put "more pressure on China" to allow for a "full, credible investigation" into the source of the global pandemic.

Fox News' Pat Ward, Rich Edson, Morgan Phillips, Edmund DeMarche, and The Associated Press, contributed to this report.