Surgeon General Jerome Adams on Sunday warned that the next week of the coronavirus pandemic will be a major moment for Americans — similar to the Sept. 11 terrorist attacks — and urged governors who have not issued statewide stay-at-home orders to “do their part.”

As of Sunday morning, nine governors ― all Republicans ― have so far refused to issue statewide stay-at-home orders despite calls from public health experts and medical professionals to do so.

Asked what he would tell those governors if he were advising them, Adams told ABC’s “This Week” that he would urge them to follow the White House’s coronavirus guidelines to slow the spread in 30 days, which include recommendations to work from home if possible and avoid discretionary travel.

“The next week is going to be our Pearl Harbor moment,” Adams said. “It’s going to be our 9/11 moment. It’s going to be the hardest moment for many Americans in their entire lives. And we really need to understand that if we want to flatten that curve and get through to the other side, everyone needs to do their part.

“If you can’t give us 30 days, governors, give us a week,” the vice admiral continued. “Give us what you can so that we don’t overwhelm our health care systems over this next week and then let’s reassess at that point.”

More than 300 million people across 41 states, Puerto Rico, and Washington, D.C., have been ordered to stay home as the virus continues to spread across the country. Arkansas, Iowa, Nebraska, North Dakota, South Dakota, Oklahoma, South Carolina, Utah and Wyoming are not under such statewide orders. (Parts of the latter four states, including several cities and counties, are subject to stay-at-home or shelter-in-place orders.)

“I wish every governor would encourage the people in their states to follow these guidelines for 30 days,” Adam said. “But I want them to do what they can in their states. ... Governors are rightly protective of their ability to determine what’s best for their citizens. We want them to have the science to make the best recommendations.”

Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and a member of the White House coronavirus task force, suggested Thursday that a national lockdown was needed to slow the spread of the virus. But President Donald Trump has so far been reluctant to do so, putting the onus on the states.

“We have a thing called the Constitution, which I cherish,” Trump said during a news briefing Saturday. “Now in some cases we’ll supersede ... If I saw something wrong, if I saw a massive outbreak, of which there’s not, I would come down very hard.”

Adams on Sunday also advised Americans to wear cloth face coverings when they’re in public to help curb the spread of the virus, as recommended by the U.S. Centers for Disease Control and Prevention on Friday.

“We always recommended if people had symptoms they wear a face mask,” Adams said. “Here’s what’s changed: We now know that about 25% ― in some studies, even more ― of COVID-19 is transmitted when you are asymptomatic and pre-symptomatic. And so the CDC has now recommended that people wear cloth face coverings when they’re going to be out in public.”

WATCH: The U.S. @Surgeon_General says don't "substitute social distancing with face masks." #IfItsSunday



Vice Adm. Adams: "We always recommended if people had symptoms they wear a face mask ... the CDC has now recommended that people wear cloth face coverings out in public." pic.twitter.com/eOQazZmOG6 — Meet the Press (@MeetThePress) April 5, 2020

During a news conference Friday, Trump acknowledged the CDC’s recommendations for face masks, but said he was “choosing not to” wear one.

Adams has faced scrutiny in recent weeks in his response to the coronavirus, including initially downplaying the threat and dodging questions last month on whether Trump should stop holding rallies and traveling.

“The president ... sleeps less than I do and he’s healthier than what I am,” Adams, who is 45, told CNN at the time.