The memo sent by acting Deputy Administrator Mike Flynn on Thursday said the agency wants to complete the buyout program by September. It did not give a dollar figure for the buyouts or say how many employees it hoped would take the offer.

The memo was sent to all employees at the same time EPA Administrator Scott Pruitt joined Trump at the White House to announce that the United States would withdraw from the Paris climate agreement.

“Early outs and buy outs … can help us realign our workforce to meet changing mission requirements and move toward new models of work,” the memo said. “The authority encourages voluntary separations and helps the Agency complete workforce restructuring with minimal disruption to the workforce.”

The EPA would see the biggest cuts of any federal agency in Trump’s 2018 budget proposal, with a 31% reduction in budget and the elimination of over 3,200 employees. The EPA employs about 15,000 people.

In the memo, Flynn said the White House Office of Management and Budget must still approve the buyout plan. The EPA and other federal agencies have offered buyouts to employees from time to time in the past.

Details on the selection criteria for employees in the pool were still being worked out, the memo said.

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Career staff at the EPA have been on edge since Trump took office, as the president vowed to undo major EPA air and water regulations in his first 100 days.

Pruitt, who was an instrumental voice in convincing Trump to withdraw the United States from the Paris climate accord, doubts that human beings drive climate change and believes the agency should pare back regulations on the energy industry.

The agency has also removed references to climate change and links to key EPA climate change reports from its website.