As Sen. Rand Paul is reiterating his intention to investigate him if Republicans win back the Senate this fall, Dr. Anthony Fauci, arguably the face of the federal government’s COVID-19 response, said Tuesday he has nothing to hide.

Paul, R-Ky., told The Hill this week, “One way or another, if we are in the majority, we will subpoena his records and he will testify in the Senate under oath.”

Fauci has served as director of the National Institute of Allergy and Infectious Diseases since 1984 and last year added chief medical adviser to President Joe Biden to his job titles.

Early in the pandemic, Fauci, along with the CDC, called for Americans to socially distance and wear masks, but he also cautioned about the potential dangers of protracted lockdowns. He became a lightning rod for criticism from Republicans, especially from then-President Donald Trump.

Paul has been one of Fauci’s sharpest critics, and the two have repeatedly clashed in Senate hearings when Fauci testified.

Paul, who is running for a third term and is line to chair a committee if the GOP takes the Senate majority, says he believes COVID-19 escaped from a lab in Wuhan, China, and that National Institutes of Health-funded “gain of function” research — the practice of enhancing a virus in a lab to study its potential impact in the real world — was partly to blame. Fauci’s NIAID is part of the National Institutes of Health. 

Fauci has denied the allegation and accused Paul and other Republican critics of distorting the facts. Sen. Ted Cruz of Texas and Rep. Jim Jordan of Ohio are among Republicans who have called for investigations into Fauci.

In an interview with CNN on Tuesday, Fauci said “there’s no reason” to investigate him and defended his guidance during the pandemic.

“But if they want to, go ahead,” he said. “My records are an open book. They are talking about things that are really bizarre … like crimes against democracy by shutting down the government. All I have ever done — and go back and look at everything I've ever done — was to recommend common sense, good, CDC-recommended public health policies that have saved millions of lives. If you want to investigate for me for that, go ahead.”

The World Health Organization has concluded that a lab origin for COVID-19 is “extremely unlikely,” while the U.S. intelligence community has been unable to reach a consensus. 

On Tuesday, the journal Science published a study that found the emergence of the virus “occurred via the live wildlife trade in China” and that “the Huanan market was the epicenter of the COVID-19 pandemic.”