The United States Postal Service is seeking a temporary waiver from the Biden administration’s mandate that will require large employers to ensure that workers are either vaccinated against COVID-19 or that they test negative weekly.

Deputy Postmaster General Douglas Tulino noted in a letter to the Occupational Safety and Health Administration that USPS could lose employees at a critical time as a consequence of the mandate.

Fox News noted that the letter warned that the mandate “is likely to result in the loss of many employees — either by employees leaving or being disciplined – particularly given the higher level of temporary employees at this time of year.”

“Given our essential role to the nation, particularly during these challenging times, we believe that it is critical to avoid disruption to our vital operations,” Tulino declared. “For that reason, we are seeking temporary relief from the ETS and maintenance of the status quo on an interim basis.”

“While the impact to our service could be devastating at any time of year, requiring the Postal Service to absorb what could inevitably be a dramatic loss of employees at a time when the labor market is extremely tight and in the middle of the Postal Service’s Peak Season would have a potentially catastrophic impact on our ability to provide service to the American public when demand is at its highest,” Tulino noted in the letter, according to the outlet.

The vaccine or test mandate applies to employers with 100 or more employees.

OSHA has declared that it “will not issue citations for noncompliance with any requirements of the ETS before January 10 and will not issue citations for noncompliance with the standard’s testing requirements before February 9, so long as an employer is exercising reasonable, good faith efforts to come into compliance with the standard.”

The nation’s high court is slated to hear arguments regarding the controversial mandate this Friday, according to reports.

“The Postal Service is seeking temporary relief because it wants to ensure that its ability to deliver mail and packages is not hindered amid the current disruptions in the nation’s supply chain,” Postal Service spokesperson Darlene Casey noted in a statement, according to the Washington Post and Fox News. “In addition, the Postal Service wants to adopt policies and procedures that comply with the [OSHA standard] while also fulfilling the organization’s other legal obligations.”