WILMINGTON, Del. — The U.S. government's top infectious disease expert, Dr. Anthony Fauci, said Sunday that he was hopeful the Food and Drug Administration will give full approval to the coronavirus vaccine by month's end and predicted the potential move will spur a wave of vaccine mandates in the private sector as well as schools and universities.

The FDA has only granted emergency-use approval of the Pfizer, Moderna and Johnson & Johnson vaccines, but the agency is expected to soon give full approval to Pfizer.

The Biden administration has stated that the federal government will not mandate vaccinations beyond the federal workforce, but is increasingly urging state and local governments as well as businesses to consider such mandates. Fauci, who is President Joe Biden's chief medical adviser, said "mandates at the local level need to be done" to help curb the spread of the virus.

"I hope — I don't predict — I hope that it will be within the next few weeks. I hope it's within the month of August," Fauci said of FDA approval of the vaccine. "If that's the case, you're going to see the empowerment of local enterprises, giving mandates that could be colleges, universities, places of business, a whole variety and I strongly support that. The time has come. ... We've got to go the extra step to get people vaccinated."

Fauci's comments come as the Biden administration is weighing what levers it can push to encourage more unvaccinated Americans to get their shots as the delta variant continues to surge through much of the United States.

Biden recently approved rules requiring federal workers to provide proof of vaccination or face regular testing, mask mandates and travel restrictions. Biden is also awaiting a formal recommendation from Defense Secretary Lloyd Austin on potentially requiring U.S. troops to get vaccinated.

The administration has become more vocal in its support of vaccine mandates at a moment when high-profile companies have informed employees that coronavirus vaccination requirements are in the works, and some localities have adopted or are contemplating vaccine requirements to dine indoors.

United Airlines informed its employees that they will need to be fully vaccinated by Oct. 25 or five weeks after the FDA grants full approval to one of the vaccines — whichever date comes first.

Disney and Walmart have announced vaccine mandates for white-collar workers, and Microsoft, Google and Facebook said they will require proof of vaccination for employees and visitors to their U.S. offices. Tyson Foods has also announced it will require all U.S. employees to get vaccinated by November.

There's also been pushback.

The U.S. Supreme Court last week was asked to block a plan by Indiana University to require students and employees to get vaccinated against COVID-19. It's the first time the high court has been asked to weigh in on a vaccine mandate and comes as some corporations, states and cities are also contemplating or have adopted vaccine requirements for workers or even to dine indoors.

Randi Weingarten, president of American Federation of Teachers union, said on Sunday that she personally supports a vaccine mandate for educators.

"As a matter of personal conscience, I think that we need to be working with our employers — not opposing them on vaccine mandates," said Weingarten, who estimated about 90% of AFT members are already vaccinated.

Dr. Francis Collins, director of the National Institutes of Health, on Sunday all but endorsed vaccine mandates, saying, "I celebrate when I see businesses deciding that they're going to mandate that for their employees."

"Yes, I think we ought to use every public health tool we can when people are dying," Collins said.

Fauci and Weingarten spoke on NBC's "Meet the Press," and Collins appeared on ABC's "This Week."