In an announcement on Wednesday, the U.S. Supreme court said that on January 7, it would hear oral arguments on separate disputes challenging the Biden administration’s mandate for businesses with more than 100 employees, and for some 17 million health care workers at facilities receiving Medicaid and Medicare funding.

The court, which has a 6-3 conservative-leaning majority, delayed action on emergency requests in both cases that sought an immediate decision. The workplace mandate is currently in effect nationwide, while the health care worker mandate is blocked in half of the 50 U.S. states.

The mandate for health care workers was issued last month by the Centers for Medicare and Medicaid Services (CMS), and affects roughly 17 million workers. It requires facilities that receive Medicare or Medicaid funding to require workers to get vaccinated, and has no testing opt-out.

The deadline for meeting the mandate is Jan. 4, 2022. However, OSHA said on Dec. 18 that it would not be issuing fines to businesses for noncompliance until Jan. 10.

The Biden administration’s private employer COVID-19 vaccine mandate, meanwhile, was promulgated by the Department of Labor’s Occupational Safety and Health Administration (OSHA). If allowed to take effect next month, it will force every business with 100 or more employees to require proof of a negative COVID-19 test on at least a weekly basis or proof of vaccination from each worker. Companies that don’t comply would face escalating fines.

The White House on Wednesday said that it is “confident in the legal authority for both policies.”

The announcement comes as the Biden administration ramps up its messaging for Americans to get vaccinated and receive their booster shots.

The Omicron variant of the novel coronavirus on Monday became the dominant source of new infections in the United States, accounting for roughly 73 percent of new infections nationwide, according to data from the Centers for Disease Control and Prevention (CDC).

Federal officials cited CDC figures for the week ending Dec. 18 that showed a nearly six-fold increase in Omicron’s share of infections in only one week.

Infectious diseases expert Dr. Anthony Fauci on Dec. 17 floated the idea of redefining what it means to be fully vaccinated in the United States.

Currently, individuals are considered fully vaccinated after taking their second dose of a two-dose series, such as the Pfizer-BioNtech vaccine, or after a single-dose vaccine, such as the Johnson & Johnson vaccine.

However, Fauci told CNBC’s “Squawk Box” last week that a redefinition of being fully vaccinated is “on the table.”  “There’s no doubt that optimum vaccination is with a booster,” he said.

“Whether or not the CDC is going to change that, it certainly is on the table and open for discussion. I’m not sure exactly when that will happen. But I think people should not lose sight of the message that there’s no doubt if you want to be optimally protected, you should get your booster.”