President Joe Biden endorsed coronavirus vaccine mandates on Thursday, using some of his strongest rhetoric to date to encourage private companies to require employees to get the vaccine.

“In addition to providing incentives to encourage vaccination, it’s time to impose requirements on key groups to make sure they’re vaccinated,” Biden said at an event at the White House, endorsing the idea of private businesses everywhere requiring their employees to get vaccinated.

“I’d like to see them continue to move in that direction,” he said, about private businesses.

He said he asked the Justice Department to issue an opinion on the legality of coronavirus vaccine mandates.

“Local communities can do that, local businesses can do that, it’s still a question whether the federal government can mandate the whole country. I don’t know that yet,” he said.

Biden said he would continue to call for more vaccine mandates.

“I’m going to keep at it,” Biden told reporters. “I’m going to be talking about it around the country.”

He defended his efforts at supporting vaccine mandates, despite shying away from tougher rhetoric on the issue in the past.

“I have made the case repeatedly,” he said. “I doubt whether there’s a single solitary business that doesn’t understand that I think it’s smart for them to require testing. And if you can’t demonstrate, you can’t prove you’ve been vaccinated, you have to be tested.”

Biden noted that corporate business groups like the Chamber of Commerce, the National Association of Manufacturers, and the Business Roundtable were all supportive of his vaccine mandate.

“Every day, more businesses are implementing their own vaccine mandates,” he said.

Biden detailed his expected announcement requiring federal government employees to get vaccinated or be subject to testing and distancing measures.

The White House said that anyone employed by the federal government who does not volunteer their vaccination information will be required to wear a mask, distance themselves from other people, get tested for the virus once or twice a week, and have their official business travel restricted.

He noted that federal contractors would be required to do the same.

“If you want to do business with the federal government, get your workers vaccinated,” Biden said.

Biden warned unvaccinated Americans that they were endangering their country by refusing to get the coronavirus vaccine.

“If, in fact, you’re unvaccinated, you present a problem to yourself, to your family, and to those with whom you work,” he said.