The Kentucky Republican has for years called for Fauci to be indicted and accused him of lying to Congress about whether the National Institutes of Health funded "gain-of-function" research in Wuhan, China, and of helping cover up the origins of COVID-19.

Fauci denies both claims and says he has testified truthfully multiple ​times before Congress on these issues.

Gain-of-function research is, broadly, work that modifies a pathogen in ways that could make it ​more transmissible or dangerous, though scientists disagree over how narrowly the term should be defined.

That disagreement is ⁠the crux of the Paul-Fauci dispute: Paul says the NIH funded such work in Wuhan and that Fauci lied when he denied it, ​while Fauci says the research did not meet the government's formal regulatory definition.

COVID-19's origins remain unresolved. The FBI said in 2023 that a leak from ​a laboratory in the central Chinese city of Wuhan likely caused the pandemic, a claim China said had "no credibility whatsoever". The CIA said in January 2025 it had shifted its assessment and concluded a lab leak was likely, but with "low confidence," while four other U.S. intelligence agencies and the National Intelligence Council believe ​the virus most likely emerged via natural transmission.

Fauci, who led the National Institute of Allergy and Infectious Diseases for 38 years, quickly ​became the most recognizable face of the U.S. pandemic response in 2020.

Ahead of the hearing, Paul this week published a 1,141-page tranche of Fauci's pandemic-era diary entries, spanning ‌December ⁠2019 through December 2022.

"Many entries in Fauci's daily historical account completely undermine the official narrative that Fauci and other public health officials espoused," he said in a statement.

A fact-check document provided by a representative of Fauci said the diary entries match what he said publicly at the time. He has said since 2021 he kept an "open mind" that COVID could have leaked from a lab, and spoke publicly in early ​2020 about asymptomatic transmission and China's ​lack of transparency, the very ⁠matters Paul says the diary reveals.

U.S. Health Secretary Robert F. Kennedy Jr., an anti-vaccine activist and, like Paul, a frequent critic of Fauci, told Fox News on Monday he handed the files to the ​senator after finding them on government servers.

Both Kennedy and Paul have signaled Fauci's testimony could expose him ​to a perjury ⁠charge despite a preemptive pardon from President Joe Biden.

Paul has for years pledged to see Fauci imprisoned.

The entries largely chronicle Fauci's media appearances and fame. A review of his public record provided by a representative of Fauci shows his positions were consistent with the diary.

The Trump administration issued ⁠a policy ​on Tuesday barring federal funding for "dangerous gain-of-function" research, the category at the heart of ​the Fauci dispute.

In April, former Fauci adviser David Morens was indicted on charges of concealing federal records about research grants and the origins of COVID, though Fauci was not ​charged. Biden preemptively pardoned Fauci in January 2025 to guard against "unjustified and politically motivated prosecutions."