(NewsNation Now) — A report in the Wall Street Journal says a U.S. government lab found the COVID-19 lab leak theory “plausible” in May 2020.

The Journal reports the Lawrence Livermore National Laboratory’s intelligence unit did the study based on genomic analysis of COVID-19.

The Chinese government has accused President Joe Biden of playing politics by warming to the idea the SARS-CoV-2 virus, which causes COVID-19, leaked from a lab. They deny it happened.

But past and present U.S. intelligence officials say China would likely never admit to a mistake like that even if they knew it to be true.

Testifying before the Senate Armed Services Committee Tuesday, former deputy national security advisor Matt Pottinger said “the preponderance circumstantial evidence” pointed toward the lab leak theory being correct.

“China does not want us to actually find the answer to the question of what exactly happened,” he said. “And I think that a bipartisan commission should be quickly established that has subpoena power.”

The lab leak theory, which still has not been proven right, is gaining mainstream acceptance after spending much of 2020 relegated to conspiracy territory.

“There’s not a single piece of evidence that points towards that stupid food market the Chinese Communist Party used as a cover story,” Republican Sen. Tom Cotton said at the hearing.

Pottinger also called for the U.S. government to reinstate an Obama-era ban on gain of function research. That’s when scientists make viruses more potent or contagious as part of an effort to better understand them. That comes with obvious risks, and recent research of that style has come under fresh scrutiny.

The virus may not have been a human construct even if it did escape from a lab. In 2020, a study done in the U.S. looked into suspected manufactured elements of the virus but ultimately found them to be natural.

Proving the lab leak theory right or wrong would likely require cooperation from China, which has little incentive to grant it. The World Health Organization has no more authority than the U.S. government to force them to be forthcoming.

“The more that the Chinese recognize that they are simply out of step with the international community, and then they are alienating countries all over the world by being uncooperative, that has the best chance [of forcing their hand],” Evan Medeiros, an expert in Asian studies at Georgetown University, said at the hearing. “But even then, this is an uphill battle.”