The early morning vote on Thursday by the Homeland Security and Governmental Affairs Committee went on party lines with Republicans in favour and Democrats opposed.
The resolution accuses Fauci, 85, of failing to obey a congressional subpoena. The move followed a hearing last week where Fauci, who retired in 2022 as the head of the national infectious-disease agency and a presidential adviser, invoked his constitutional right against self-incrimination more than 100 times.
Republican Senator Rand Paul said he would refer Fauci to the Justice Department, a formal request to consider criminal charges, based on the contempt finding. But the Kentucky senator, a longtime Fauci antagonist, bypassed a referral vote by the full Senate.
He described that step as unnecessary and said his request would be hand delivered to the attorney-general on Thursday. Democrats said Paul was violating Senate rules by skipping the vote, which would likely fail to achieve the necessary 60-vote majority, and called the move dangerous and unprecedented.
The development was the sharpest escalation yet in a broad Republican and Trump administration campaign to re-litigate the pandemic and assign blame for the toll of actions taken as part of the US response.
President Donald Trump said the Justice Department should potentially prosecute Fauci, comparing him to allies Peter Navarro and Steve Bannon, who both served four months in prison for contempt of Congress after defying subpoenas.
"Maybe he should. What he did was far more serious than a lot of crimes, frankly," Trump told reporters in the Oval Office when asked if Fauci should be prosecuted.
Fauci's lawyer, David Schertler, said Thursday's vote was "a crude political stunt intended to punish Dr. Fauci for exercising his constitutional rights."
"Dr Fauci has committed no crime — and Senator Paul knows it," Schertler said, describing the resolution as a continuation of a "personal vendetta."
Paul denied this, saying in his opening statement: "Seeking the truth is not a witch hunt."
He said the committee was seeking accountability to prevent "a repeat of the mistakes and the very real consequences of the past".
Fauci, who led the National Institute of Allergy and Infectious Diseases for 38 years, became the face of the US COVID-19 pandemic response and a primary target of anger over measures taken against a virus that killed more than 1.1 million Americans.
Paul and other Republicans have pursued a years-long investigation, including hard-nosed tactics such as publishing Fauci's daily diary entries and obtaining the contents of his phone, in a bid to prove Republican assertions that Fauci orchestrated a cover-up of the coronavirus' origins.
The senator claims Fauci's institute funded risky virus research in China that sparked the pandemic through a lab leak there. Fauci denies the accusation, and the National Institutes of Health has also rejected it, saying the viruses studied with US funding differed from the one that caused COVID-19.
US intelligence agencies and scientists remain divided over whether a lab leak or natural transmission from animals sparked the pandemic.
Trump and many conservatives criticised Fauci's handling of COVID-19 including his guidance on lockdowns, mask-wearing, social distancing and vaccines. While Fauci's recommendations were backed by then-current science, the issue became heavily politicised.
Former president Joe Biden pre-emptively pardoned Fauci in January 2025 to guard against "unjustified and politically motivated prosecutions" related to COVID or his role in the response.
The pardon does not cover subsequent conduct. Paul said Fauci had no valid Fifth Amendment claim because the pardon nullified it and because Fauci waived any remaining protection by testifying.
Contempt of Congress, a federal misdemeanour, can be punished with a fine of up to $US100,000 ($A142,000) and up to 12 months in prison.
