US President Joe Biden has ordered sweeping new federal vaccine requirements for as many as 100 million Americans in an all-out effort to increase COVID-19 vaccinations and curb the surging Delta variant.

Speaking at the White House, Mr Biden sharply criticised the tens of millions of Americans who are not yet vaccinated despite months of availability and incentives.

“This is a pandemic of the unvaccinated,” President Biden said on Thursday (local time).

“We’ve been patient. But our patience is wearing thin, and your refusal has cost all of us.”

The unvaccinated minority “can cause a lot of damage, and they are” he added.

He said despite having “unprecedented and successful vaccination programs” and free vaccines available for almost five months, 80 million Americans had failed to come forward.

“The unvaccinated overcrowd our hospitals, are overrunning emergency rooms and intensive care units, leaving no room for someone with a heart attack or pancreatitis or cancer.”

He also blasted the elected officials who have undermined the rollout by refusing to encourage their communities to get vaccinated, instead “ordering mobile morgues” for the unvaccinated.

US President Joe Biden has ramped up vaccine rules in the USA. Photo: Getty

Republican leaders and some union chiefs said Mr Biden was going too far in trying to muscle private companies and workers.

Governor Henry McMaster of South Carolina said “Biden and the radical Democrats (have) thumbed their noses at the Constitution”, while American Federation of Government Employees national president Everett Kelley insisted that “changes like this should be negotiated with our bargaining units where appropriate”.

However, there was strong praise from the American Medical Association, the National Association of Manufacturers and the Business Roundtable.

The expansive rules mandate that all employers with more than 100 workers require them to be vaccinated or test for the virus weekly, affecting about 80 million Americans.

And the 17 million workers at health facilities that receive federal Medicare or Medicaid will also have to be fully vaccinated.

Mr Biden is also requiring vaccination for federal government employees and contractors, with no option to test out. That covers several million more workers.

Tweet from @POTUS

The new requirements are part of a new “action plan” to address the latest rise in coronavirus cases and the stagnating pace of COVID-19 shots.

Just two months ago, Mr Biden prematurely declared the nation’s “independence” from the virus.

Now, despite more than 208 million Americans having at least one vaccine dose, the US has about 300 per cent more new COVID-19 infections a day and nearly twice the number of deaths compared with this time last year.

About 80 million people remain unvaccinated.

After months of using promotions to drive the vaccination rate, Mr Biden is taking a much firmer hand, as he blames people who have not yet received shots for the sharp rise in cases killing more than 1000 people a day and imperilling a fragile economic rebound.

Federal fines will double for airline passengers who refuse to wear masks on flights or to maintain face covering requirements on federal property.

First offenders face a $US1000 ($1355) penalty.

Mr Biden announced the government would work to increase the supply of virus tests, and retailers including Walmart and Amazon would sell at-home testing kits at cost beginning this week.

The administration is also sending additional federal support to help schools operate safely, including additional funding for testing.

And Mr Biden called for large entertainment venues and arenas to require vaccinations or proof of a negative test for entry.

The vaccination and testing requirement for large companies will be enacted through a forthcoming rule that carries penalties of $US14,000 per violation.

-with AAP