When Sesame Street’s Big Bird announced early in November that he had been vaccinated against Covid-19, as part of an effort by public television stations to educate families about the availability of vaccines for children age 5 to 11, Texas Senator Ted Cruz blew a gasket.

The message from the beloved children’s character was a gentler take on what public health officials have been saying to reassure kids about the jabs: “I got the COVID-19 vaccine today! My wing is feeling a little sore, but it’ll give my body an extra protective boost that keeps me and others healthy. Ms. @EricaRHill even said I’ve been getting vaccines since I was a little bird. I had no idea!”

But Cruz saw sinister machinations in the messaging. He labeled the Muppet’s announcement “Government propaganda…for your 5 year old!”

That earned the senator mockery from NBC’s Saturday Night Live, and from veteran Cruz watchers such as CNN’s Chris Cillizza, who wrote, “This is, in a word, dumb. The idea that Big Bird is some sort of Deep State propagandist is roughly as credible as the notion that Ted Cruz is the Zodiac Killer. Or that Ted Cruz’s father was involved in the assassination of John F. Kennedy.” (The former charge was a popular social media meme when Cruz mounted his failed presidential bid in 2016, while the latter was amplified during the course of that year’s campaign by the Republican candidate who shredded Cruz in the race for the Republican nod, Donald Trump.)

Attacking Big Bird didn’t work out so well for Cruz, the most notorious publicity hound in a Senate filled with headline-grabbers. So this week he’s gone back to the tried and true Republican strategy of attacking Dr. Anthony Fauci, the 80-year-old immunologist who directs the National Institute of Allergy and Infectious Diseases and serves as chief medical adviser to President Joe Biden.

“Fauci is an unelected technocrat who has distorted science and facts in order to exercise authoritarian control over millions of Americans,” tweeted Cruz on Sunday after the doctor appeared on CBS’s Face the Nation. “He lives in a liberal world where his smug ‘I REPRESENT science’ attitude is praised.”

Cruz’s crusade to discredit the physician and scientists fits in with what columnist S.E. Cupp refers to as “The right’s Fauci Derangement Syndrome.” In October, the senator went so far as to call for a special prosecutor to be appointed to investigate Fauci.

When asked about that threat in Sunday’s CBS interview, Fauci said, “I have to laugh at that. I should be prosecuted? What happened on January 6, senator?”

Stung by the reference to his amplifying of the Big Lie about the 2020 election results that inspired insurrectionists to attack the US Capitol, Cruz again tore into Fauci, calling the doctor “the most dangerous bureaucrat in the history of the country.” He went on to say: “I don’t think anyone has hurt science, has hurt the credibility of the CDC, has hurt the credibility of doctors, more than Dr. Fauci, because throughout this pandemic, he’s been dishonest. He’s been political. He’s been partisan, and the American people know it.”

Cruz’s anti-Fauci ranting peddled falsehoods so outrageous that a previous Washington Post fact-check awarded them “Two Pinocchios.” But his lies went unchallenged as he made them on Fox News, which recently drew sharp criticism from the Anti-Defamation League, the Auschwitz Museum, and the American Jewish Committee after Fox personality Lara Logan went on Fox News Primetime and compared Fauci with Josef Mengele, the Nazi doctor who committed atrocities with medical experiments on Jews in death camps. The network’s top host, Tucker Carlson, has also derided Fauci, calling the former adviser to President Trump “a shorter version of Benito Mussolini.”

The language employed by the senator from Texas and his media echo chamber is so over the top that it’s easy to write off what Cruz says about Fauci as nothing more than the political claptrap that spews from the mouth of a once and future failed presidential contender. But there’s a serious side to what’s happening here. Cruz and other Republicans in prominent positions are seeking to discredit Fauci at precisely the point when Americans should be taking seriously the immunologist’s counsel about the need to get vaccinated and take precautions.

The pandemic is surging in many parts of the country—especially in regions where vaccine hesitancy is high and vaccination rates are low—and the death toll has surpassed 777,000. With a new variant in motion, the senator’s current assault on Fauci is more than a clash of personalities. Cruz is spreading misinformation that puts people in danger, especially conservatives who take the Texan at his word.

Public health experts have been counseling this week about the need to take precautions against the general spread of the virus, which is all but inevitable this time of year, and the Omicron variant, which has now arrived in the United States. Yet Cruz is using his platform as one of the best-known members of Congress to tell people to adopt a dismissive attitude toward existing threats and those that may develop.

“There’s always going to be a new variant,” he told Sean Hannity this week. “Joe Biden and the Democrats need to stop threatening shutdowns of schools, stop threatening shutdowns of business. Enough is enough.”

Cruz would have us believe that Anthony Fauci—and Big Bird—are spreading the virus of governmental overreach to the detriment of American freedom. In fact, Ted Cruz is spreading the virus of disinformation and distrust to the detriment of American health, and American lives.