(CNN)President Joe Biden on Thursday imposed stringent new vaccine rules on federal workers, large employers and health care staff in a sweeping attempt to contain the latest surge of Covid-19.The new requirements could apply to as many as 100 million Americans — close to two-thirds of the American workforce — and amount to Biden’s strongest push yet to require vaccines for much of the country.“We’ve been patient, but our patience is wearing thin, and your refusal has cost all of us,” Biden said, his tone hardening toward Americans who still refuse to receive a vaccine despite ample evidence of their safety and full approval of one — the Pfizer-BioNTech Covid-19 vaccine — from the US Food and Drug Administration.He said vaccinated America was growing “frustrated” with the 80 million people who have not received shots and are fueling the spread of the virus. And he acknowledged the new steps would not provide a quick fix.“While America is in much better shape than it was seven months ago when I took office, I need to tell you a second fact: We’re in a tough stretch and it could last for awhile,” Biden said in an early evening speech from the White House.At the center of Biden’s new plan is directing the Labor Department to require all businesses with 100 or more employees ensure their workers are either vaccinated or tested once a week, an expansive step the President took after consultation with administration health officials and lawyers. Companies could face thousands of dollars in fines per employee if they don’t comply.Biden also signed an executive order requiring all government employees be vaccinated against Covid-19, with no option of being regularly tested to opt out. The President signed an accompanying order directing the same standard be applied to employees of contractors who do business with the federal government.He also said 300,000 educators in federal Head Start programs must be vaccinated and called on governors to require vaccinations for schoolteachers and staff.And Biden announced he would require the 17 million health care workers at facilities receiving funds from Medicare and Medicaid to be fully vaccinated, expanding the mandate to hospitals, home care facilities and dialysis centers around the country.“We have the tools to combat the virus if we come together to use those tools,” Biden said at the outset of what was billed as a major speech to tackle the latest phase of the Covid-19 pandemic.The new rules amount to the most dramatic steps to date to get more Americans vaccinated. Once cautious of vaccine mandates, the Biden administration is now wholly embracing them as vaccine hesitancy persists among certain groups.Administration officials acknowledged the requirement for large employers could be challenged in court. But they said their hope was to provide cover of federal rules to businesses who want to require vaccines for employees.The new rules come as the Delta variant tears through communities across the country, causing upticks in hospitalizations and deaths particularly in areas where vaccination rates remain low.