For much of the past year, Republicans have decried lead government coronavirus expert Anthony S. Fauci’s prescriptions for mitigating the pandemic — including masks, social distancing and keeping society shut down.

But increasingly in the past week, the effort has taken on a new flavor — with suggestions that Fauci might be personally to blame for the advent of the virus itself.

There remain major questions about just how the virus emerged, including the idea that it somehow escaped a lab in the city of Wuhan, China, where the virus originated. The theory, which was once highly speculative and which was downplayed by top medical experts such as Fauci, is suddenly being treated more seriously, though there is no conclusive evidence either way.

But while some Republicans have criticized the initial dismissal of that theory as evidence of a lack of curiosity from the media and health officials about the origins of the virus — or even some kind of pro-China or anti-Trump bias — the theories about Fauci’s complicity take things to another level.

With Fauci set to testify before the Senate on Tuesday, Fox News host Tucker Carlson teed things up the night before. In a commentary leading off his show, he played up the idea of a lab leak, pointing (rightly) to shifting beliefs in the medical community about its plausibility and treating it as an open question.

But then he pivoted to treating this as something amounting to fact.

While talking about National Institutes of Health funding for the Wuhan Institute of Virology, Carlson referred to “the deadly experiments that were going on there” — which is valid, given that’s the kind of thing virologists do.

But he then referred to them, as if the lab-leak theory were proved, as “the experiments that clearly went so wrong.”

Again, there is no firm evidence that the spread of the coronavirus was the result of experiments that “clearly” went “so wrong” in the Wuhan lab. Carlson has a knack for suggesting things without saying them directly, but this veered in a much more conspiratorial and unproven direction than usual.

“This wouldn’t have happened if Tony Fauci didn’t allow it to happen — that is clear,” Carlson continued, referring to the funding. “It’s an amazing story. It is a shocking story. In a functional country, there would be a criminal investigation into Tony Fauci’s role in the covid pandemic that has killed millions and halted our country, changing it forever."

The easy answer is that it’s speculative and that criminal investigations generally involve some kind of genuine evidence of wrongdoing or violations of specific laws. It has been known for a long time that U.S. health agencies funded the Wuhan Institute of Virology, and it’s valid to ask whether that funding was a good idea. But there is no evidence that such funding ran afoul of U.S. law or that it contributed to the pandemic.

Update: Carlson doubled down Tuesday night on the unproven lab leak theory and Fauci’s supposed responsibility for it, suggesting Fauci should not just be investigated but indicted. “The guy in charge of America’s response to covid turns out to be the guy who funded the creation of covid,” Carlson said, again going much further than the evidence allows. And Carlson’s guest, coronanvirus and vaccine skeptic Alex Berenson, actually pushed back on the idea of Fauci’s culpability.

GOP senators picked up that ball and ran with it Tuesday, pressing Fauci on the idea that funding the Wuhan lab put him at fault.

Sen. Rand Paul (R-Ky.), who has clashed repeatedly with Fauci, pressed him on funding for the Wuhan lab. Paul suggested that the funding ran afoul of a prohibition on “gain-of-function” research — i.e., altering genomes to give viruses new properties, such as the ability to infect a new host species or to transmit more easily. The idea behind such research is that it might provide insight into how a virus spreads and improve efforts to counteract it, though it also carries obvious risks, which is why funding for such research is limited.

Paul claimed that the U.S. government was downplaying the link between gain-of-function research and the coronavirus because it was “self-interested” in continuing such research, or even covering up its role in the pandemic. He went on to press Fauci on the funding for the Wuhan lab, at which point Fauci said repeatedly that such funding was not intended to fund gain-of-function research (which fact-checkers have validated).

“With all due respect, you are entirely and completely incorrect that — the NIH has not ever and does not now fund gain-of-function research in the Wuhan Institute,” Fauci said.

Paul then reverted to pointing to alleged gain-of-function research that is taking place in the United States, rather than the Wuhan lab, to which Fauci offered a rather lawyerly response about what gain-of-function research is. Paul then pressed him on sending broader funding to the Wuhan lab.

Fauci did at one point say about the lab-leak theory: “I do not have any accounting of what the Chinese may have done, and I am fully in favor of any further investigation of what went on in China.”

Paul later got some backup from Sen. Roger Marshall (R-Kan.).

Marshall, who like Paul is a doctor, repeatedly pressed Fauci on the idea that such viral research could have led to the novel coronavirus. He asked whether Fauci could definitively say that NIH funding didn’t, in some way, play a part in a theoretical eventual lab leak, citing research on mice.

“Could some of the funding [have] indirectly ended up to the contribution of covid-19?” Marshall asked.

Fauci, testily, responded that the question was excessively broad, because many types of research could conceivably meet the definition as having one day contributed to the spread of the virus.

“I’m not sure exactly where that question is going,” Fauci said. “I mean, you could do research on something as benign as looking at something that has nothing to do with it, and it could, indirectly, some day, somehow be involved. So if you want to trap me into saying yes or no, I’m not going to play that game.”

There are valid questions about the lab-leak theory and whether funding the Wuhan lab was a good idea, in light of all we know. And Fauci acknowledges it’s worth figuring out whether the lab and China more broadly played a role. But as always in politics, it’s worth being skeptical of a conveniently erected boogeyman.

The idea that Fauci is somehow using all of this to keep people in masks or locked down for his own edification has been a fixture in some corners of conservative media, and in their telling he’s gradually emerged as perhaps the epitome of overzealous government scientists. But this new line of attack is painting him as something else entirely.