If the federal government sticks to a pending mandate that almost all employees of federal contractors must be vaccinated against COVID-19, it could still take “months” to layoff unvaccinated employees, the chief executive of one of the top government services companies said on Tuesday.

Unvaccinated employees would go through the typical disciplinary actions, which include oral and written processes and then go before the employee disciplinary board, Roger Krone, chairman and CEO of Leidos [LDOS], said during the company’s third quarter earnings call.

The Biden administration has given federal contractors until Dec. 8 to ensure their employees are vaccinated, but there are still relatively large percentages of employees who have refused so far, leading to concerns in the defense space that work will slow if thousands of workers quit over the mandate.

“It is unlikely that we would involuntarily separate employees early but there is a possibility that at some point we’re going to have to lay off some people because they don’t get vaccinated,” he said.

Krone said that based on vaccination cards that employees have uploaded so far, the company’s vaccination rate is believed to be in the mid-90 percent range. Last week, General Dynamics [GD] said about 75 percent of its employees are vaccinated.

Leidos held a “needle sweepstakes” for its employees that helped drive up company-wide vaccination rates. The company offered payments of full-year salary that 10 employees won during the effort to get personnel to receive the vaccinations, Krone said.

Leidos is working with the White House and legislators on “a sensible implementation” of the vaccine mandate, Krone said, highlighting that the situation is “fluid” amid the possibility that the administration could relax the deadline and because some states are saying companies and citizens in their jurisdictions don’t have to comply with the mandate.

President Biden’s executive order from September on the vaccine mandate for federal contractors provides exemptions for health and religious reasons. Still, Krone said, “We worry about a small percentage number of people” that won’t apply for an exemption and will refuse to be vaccinated.

“What we want to do is keep Covid out of our facilities and out of our customer facilities and the executive order gives us a great opportunity to do that and we’re going to everything in our power to keep Covid out and be compliant with the rules and laws and the executive order but we care about our employees, we are a people company and our workforce is really, really important and we’re going to do all we can to maintain jobs for our employees,” Krone said.

Krone touted one option Leidos has for its employees that work on federal contracts is the fact that the company does have commercial clients, so employees on these accounts are not subject to the mandate. If the skillsets match, people that don’t want to be vaccinated that are federal contractors can move to open jobs with commercial customers, he said.

Leidos is encouraging “non-vaccinators, if they would like,” to take open jobs in commercial work with the company, Krone said.