The Environmental Protection Agency’s acting administrator, Catherine McCabe, told employees this week that the Trump administration’s federal hiring freeze “is already creating some challenges to our ability to get the agency’s work done.”

The comments came in a weekly video update that McCabe, a career EPA employee who previously served as a top official in its New York regional office, has been producing for staff since President Trump took office last month.

Virtually each week, she has sought to reassure EPA employees who privately — and publicly in some cases — have expressed concerns about Trump’s promises to scale back the agency’s regulatory role and his nomination of Oklahoma Attorney General Scott Pruitt, a longtime EPA antagonist, as its next leader.

“We do recognize the transition has brought some challenges,” McCabe says in the most recent video, adding, “Whatever changes and challenges come, we know we can count on you to respond with professionalism. We will continue to do our best to ensure that this agency’s decisions and actions are based on our two bedrock principles: carrying out the law and ensuring that the best science informs all that we do.”

McCabe didn’t elaborate on specific ways that the hiring freeze is hindering EPA’s work, but her brief comments echoed other government officials, who have argued that such a freeze is shortsighted.

At a Senate hearing last week, representatives from the Federal Managers Association (FMA) and the Senior Executives Association (SEA) outlined ways in which the freeze is potentially detrimental and counterproductive.

“The American taxpayer would be better served with improvements to the workforce, not blind cuts,” FMA President Renee M. Johnson said at the hearing. “All federal agencies should be allowed to match hiring actions that align with essential mission and funding.”

SEA President Bill Valdez said he fears the freeze could “have a chilling effect on the ability of the federal government to attract and recruit talent it needs, particularly from veterans, millennials, including students graduating college this spring, and to fill mission critical-skills gaps.”

The EPA has been among the agencies on the tightest leash since Trump took office. Employees have been limited in their ability to communicate publicly — the EPA has not tweeted since Trump took office, for example — and the new administration initially froze billions of dollars in grants and contracts.

Trump officials late last month lifted the temporary freeze on grants, saying programs will continue as planned. That move continued billions of dollars in revolving funds to states and Native American tribes.

In her message to employees this week, McCabe thanked members of Trump’s transition team for their “professionalism and courtesy” as they have “worked very hard to learn about the wide scope of the work we do here.”

She said Pruitt could be confirmed by the Senate as the agency’s new administrator by week’s end, although the precise timing of that vote remained uncertain Wednesday.