A prominent US senator has pledged a vigorous review into the origins of the coronavirus if republicans retake the Senate and he lands a committee chairmanship.

Speaking to supporters at a campaign rally, the libertarian-leaning Kentucky republican Rand Paul denounced what he sees as government overreach in response to the COVID-19 pandemic. 

He applauded a recent judge’s order that voided the federal mask mandate on planes and trains and in travel hubs.

“Last week I was on an airplane for the first time in two years and didn’t have to wear a mask,” he said, drawing cheers from the partisan crowd. 

“And you know what I saw in the airport? I saw at least 97 per cent of the other free individuals not wearing masks.”

Paul has clashed repeatedly with Dr Anthony Fauci, the country’s top infectious diseases expert, over the government’s COVID-19 policies and the origins of the virus that caused the global pandemic.

Paul, who is seeking a third term this year in Kentucky, said he is in line to assume a committee chairmanship if the republicans win Senate control in November’s election. 

The Senate currently has a 50-50 split, but democrats have the slim edge because Vice President Kamala Harris holds a tie-breaking vote.

“When we take over in November, I will be chairman of a committee and I will have subpoena power,” Paul said. 

“And we will get to the bottom of where this virus came from.”

The senator, an eye surgeon, continued to offer his theory about the origins of the virus.

“If you look at the evidence, overwhelmingly, not 100 per cent, but overwhelmingly the evidence points to this virus being a leak from a lab,” Paul said.

In the US, many conservatives have accused Chinese scientists of developing COVID-19 in a lab and allowing it to leak.

Intelligence agencies remain divided on the origins of the coronavirus but believe China’s leaders did not know about the virus before the start of the global pandemic, according to a review ordered by President Joe Biden and released last summer.

The scientific consensus remains the virus most likely migrated from animals in what is known as a zoonotic transmission. So-called “spillover events” occur in nature, and there are at least two coronaviruses that evolved in bats and caused human epidemics, SARS1 and MERS.

In his speech, Paul continued to rail against socialism, saying it would encroach on individual liberties. 

“When President Trump said he wanted to ‘Make America Great Again,’ I said, ‘Amen,'” Paul said. 

“But let’s understand what made America great in the first place, and that’s freedom, constitutionally guaranteed liberty.”

Kentucky has not elected a democrat to the Senate since Wendell Ford in 1992.