Senior White House officials have pushed U.S. spy agencies to hunt for evidence to support an unsubstantiated theory that a government laboratory in Wuhan, China, was the origin of the coronavirus outbreak, The New York Times reports citing current and former U.S. officials.

The effort comes as U.S. President Donald Trump escalates a public campaign to blame China for the pandemic.

Some intelligence analysts are concerned that the pressure from administration officials will distort assessments about the virus and that they could be used as a political weapon in an intensifying battle with China over a disease that has infected more than 3 million people across the globe.

Most intelligence agencies remain skeptical that conclusive evidence of a link to a lab can be found, and scientists who have studied the genetics of the coronavirus say that the overwhelming probability is that it leapt from animal to human in a nonlaboratory setting, as was the case with HIV, Ebola and SARS.

Trump’s aides and Republicans in Congress have sought to blame China for the pandemic in part to deflect criticism of the administration’s mismanagement of the crisis in the United States, which now has more coronavirus cases than any country. More than 1 million Americans have been infected, and more than 60,000 have died.