EXCLUSIVE: Customs and Border Protection (CBP) has told supervisors they must push employees on their compliance with the Biden administration's vaccine mandate or else potentially be fired themselves -- as the agency grapples with significant pushback internally to the vaccine mandates.

In an Oct 30 email, obtained by Fox News, CBP references the Sept. 9 executive order by President Biden which mandates that all federal employees be fully vaccinated by Nov. 22.

VACCINE MANDATE COULD COST BORDER PATROL MORE THAN HALF OF ITS AGENTS, INTERNAL REPORT SAYS 

"Pursuant to this requirement, all U.S. Customs and Border Protection (CBP) supervisors are ordered to have a discussion with each of their employees (direct reports)," the email says. 

During those discussions, supervisors are ordered to tell employees to upload their vaccination status and documentation by Nov. 8, and that failing to do so will have consequences of non-compliance. They are also to tell employees that they must receive their final vaccination shot by Nov. 8 to be fully vaccinated by the deadline.

FILE - A Border Patrol agent talks to migrants after they were detained and taken into custody, March 21, 2021, in Abram-Perezville, Texas. Biden took office on Jan. 20 and almost immediately, numbers of migrants exceeded expectations. (AP Photo/Julio Cortez, File)

"Supervisors who fail to have the required discussions with their employees will be subject to potential discipline for insubordination, up to removal from federal service," the email says.

The email includes "discussion points" and a discussion log that supervisors are required to submit.

Additionally, a Border Patrol source told Fox that in the coming weeks supervisors will be expected to hold counseling sessions for employees who are unvaccinated to set up a vaccination timeline. Should employees fail to comply, then they will be suspended and the termination process will begin, the source said. The source also described a work environment where agents are peppered with multiple emails a day on the subject, including videos of CBP or Homeland Security employees affected by COVID-19.

A CBP spokesperson told Fox News the agency does not comment on purportedly leaked information or documents, but said that CBP, along with other federal agencies are "laser-focused on vaccinating their workforce ahead of the November 22nd deadline for Federal employees."

"Like other Federal agencies, we are continuing to collect vaccination information from employees as we approach the deadline," the spokesperson said.

Former acting CBP Commissioner Mark Morgan told Fox News that the fact that the agency is having to push supervisors so hard shows that the mandate has been a "colossal failure across the board."

"One sure indicator that your policy is way off is when you can't get your subordinate field leadership to comply. When you're having to strong-arm your field leadership to force compliance, that's a red flag," Morgan, who served as acting CBP chief during the Trump administration, said.

Morgan had previously provided Fox News with internal CBP data that show that as of Oct 25, 48% of Border Patrol agents have not responded to the reporting mandate, and that 90% of those who had had received at least one dose. Among CBP more broadly, 32% of staff have not responded and of those that did 84% have received at least one vaccine shot.

VACCINE MANDATES COULD LEAD TO POLICE AND FIREFIGHTER EXODUSES IN URBAN AREAS

Much of the focus has been on the impact on Border Patrol in the midst of the crisis at the southern border, where more than 192,000 migrants were encountered in September alone and more than 1.7 million in Fiscal Year 2021. However, Border Patrol is just one part of CBP, and so the ramifications of a loss of staff beyond Border Patrol would have effects in other parts of CBP’s mission as well -- including ports of entry and elsewhere. 

Morgan highlighted the time commitment it would take to coordinate meetings with tens of thousands of CBP employees.

"They have to develop databases, they have to develop policy, send it out and now they mandate every single supervisor speak to every single one of the 64,000 employees -- just think of the man hours it takes to do that alone," he said.

He said that, at least for Border Patrol, many of those not complying have in fact been vaccinated but are taking a stand against what they see as a politically-motivated mandate. 

"This is not about anti-vaccine, this is about this is one of the rare opportunities for Border Patrol agents specifically, they feel they have an opportunity to make a statement, take a stand."

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Multiple Border Patrol agents who have spoken to Fox News in recent months have echoed that sentiment and have told Fox they are vaccinated but object to the mandate, particularly considering there is no such mandate for those crossing the border illegally.

"For two years Border Patrol agents have had to go on the line risking their lives and apprehend illegal aliens," Morgan said. "And now according to ‘the science’ they have to get vaccinated or lose their job but the very illegal aliens they're apprehending, they don't have to get vaccinated -- that's nonsensical. That’s not following the science."

Fox News' Tyler O'Neill contributed to this report.