She turned to Robert Redfield, the director of the Centers for Disease Control and Prevention, and quickly transformed her demeanor from an amiable game-show host into a formidable principal doling out discipline.

“Doctor Redfield,” she asked, “do you want to know who has the coronavirus and who doesn’t? Not just rich people, but everybody who might have the virus?”

It was the beginning of a relentless line of questioning from Porter that, in just five minutes, would pry a promise out of Redfield to ensure that coronavirus testing would be free for all Americans. The stunning exchange between the doctor and lawmaker, during a House Oversight and Reform Committee hearing, led many to credit Porter with potentially saving lives amid the federal government’s uneven response to the pandemic, calling her “brilliant” and a “hero.”

“How many lives did Katie Porter save today using a whiteboard, a bull---- detector, and an ability to retain focus?” television producer Hart Hanson wrote on Twitter, linking to a video of Porter’s questioning that has since been viewed nearly 20 million times.

Thursday’s hearing focused on problems with the government’s response to the novel coronavirus, particularly the utter dearth of available diagnostic tests. Despite assurances from President Trump that the process is “very smooth,” the lack of testing has raised questions about barriers to identifying coronavirus patients if people can’t get tested in the first place. Porter was additionally worried about a financial barrier: that uninsured or underinsured Americans would forgo seeking testing out of fear of the medical costs.

In five minutes, Porter sought to dismantle that barrier altogether.

She began grilling Redfield by pointing to a federal statute that gives the CDC director the power to “authorize payment for the care and treatment of patients subject to medical examination, quarantine, isolation, and conditional release.” The existing statute, Porter argued, meant that the federal government should be able to pay for everyone’s coronavirus tests without needing any new legislation.

“Doctor Redfield, will you commit the CDC right now to using that existing authority to pay for diagnostic testing free to every American, regardless of insurance?” she asked.

“Well,” he replied, “I can say we’re going to do everything to make sure everybody can get the care they — ”

Porter interrupted him: “Nope, not good enough. Reclaiming my time."

She asked him the same question again, this time more sternly, more impatiently.

“What I’m going to say is,” Redfield responded, “I’m going to review it in detail with the CDC and the department.”

“No,” Porter shot back. And again: “I’m reclaiming my time.”

At that point, Porter said she and two colleagues had already sent a letter to HHS seeking responses by Wednesday about how the agency planned to tackle insurance issues with coronavirus testing — and the agency had already blown that deadline. Now, she said, he still wasn’t giving an answer.

So she asked Redfield a third time: “Will you commit to invoking your existing authority under 42 CFR 71.30 to provide coronavirus testing for every American regardless of insurance coverage?”

“What I was trying to say,” Redfield tried again, “is that CDC is working with HHS now to see how we operationalize that.”

Disappointment flushed over Porter’s face, as she said he hoped that response would “weigh heavily” on him.

“Doctor Redfield,” she said, “you don’t need to do any work to ‘operationalize.' You need to make a commitment to the American people so they come in to get tested. You can operationalize the payment structure tomorrow."

And with that, the doctor waved a white flag.

“I think you’re an excellent questioner,” he said, “so my answer is yes.”

“Excellent,” Porter responded. “Everybody in America hear that? You are eligible to go get tested for coronavirus and have that covered regardless of insurance.”

The immediate impact of Porter’s apparent victory is unclear, especially given the lack of tests available at hospitals nationwide. As The Washington Post reported earlier Thursday, Redfield appeared to return to vague answers toward the end of the hearing that suggested he was only planning to look into free testing, saying that the administration “is currently examining all avenues” for the uninsured to afford tests and treatment.

The CDC did not immediately respond to a request for clarification.

Nevertheless, praise poured in for Porter.

“How Rep. Katie Porter, at a coronavirus hearing, may have saved your life,” read an opinion headline in the Arizona Republic.

“Katie Porter is the hero we need,” wrote actor George Takei on Twitter. “She is astonishing here.”

For some who viewed the clip of Porter’s relentless questioning, like actor Chris Pratt, it was their first introduction to Porter’s style. Porter, a consumer protection attorney who studied law at Harvard under Sen. Elizabeth Warren (D-Mass.), has become known for her tenacious questioning on the Hill after flipping a GOP district in Orange County, Calif., in 2018 to take her seat in Congress.

“I’ve never heard of this woman before,” Pratt said. “But I’m damn glad she’s up there doing her job for all of us.”

Appearing on MSNBC later Thursday, Porter said she took Redfield’s answer to her question as a “promise” and expected him to keep it.

“The CDC director made that commitment today under oath. He was sworn in at the start of that hearing, and my job as a Congress member is to ask those tough questions and to extract those promises,” Porter said. “That was a promise he made to the American people, and I intend to hold him to it.”