WASHINGTON ― Multiple federal agencies have told their employees to cease communications with members of Congress and the press, sources have told The Huffington Post.

The freeze has startled aides on the Hill and people at those agencies, who worry that it could abruptly upend current operations and stifle work and discussions that routinely take place between branches of government.

Officials at sub-agencies of the Department of Health and Human Services, for example, have been told not to send “any correspondence to public officials” according to a memo shared with HuffPost. Instead, they have been asked to refer questions to agency leadership until the leadership has had time to meet with incoming White House staff about the new administration’s policies and objectives, according to a congressional official who was also informed of the communications freeze.

An official with the National Institutes of Health told HuffPost that an email had been sent to the directors of NIH institutes and centers providing guidance from HHS on how to handle new or pending regulation, policy or guidance.

“The HHS guidance instructs HHS Operating Divisions to hold on publishing new rules or guidance in the Federal Register or other public forums and discussing them with public officials until the Administration has had an opportunity to review them,” the official said.

It’s unclear how wide the freeze goes, however, as an official close to the Centers for Disease Control and Prevention said that agency was unaware of any such freeze.

And Bill Hall, a spokesman for HHS, said that the agency was not restricting all forms of communications with the public or the media but instead was directing officials to limit communications about proposed or pending regulations. “There is no directive to do otherwise.”

That said, there also appears to be a lockdown on external communication at the Environmental Protection Agency. As HuffPost reported Monday, a memo went out within the agency following a briefing for communication directors. The memo said there would be no press releases, social media posts or blog messages until further notice. It also asked for a list of external speaking engagements for staff and any planned webinars. It warned that listservs would be reviewed and that staff should “only send out critical messages, as messages can be shared broadly and end up in the press.”

The EPA has frozen its grants as well, sources told HuffPost on Monday. ProPublica later confirmed that freeze, as well as a stop on federal contracts, in an interview with transition sources.

A source who works closely with states and territories on EPA grants said they heard from the agency on Tuesday evening that a review of grants would be done by Friday.

A similar directive has been issued to staffers at the U.S. Department of Agriculture’s research arm, BuzzFeed News reported Tuesday. The Agricultural Research Service employs 2,000 scientists and postdoctoral researchers. “Starting immediately and until further notice, ARS will not release any public-facing documents,” wrote Sharon Drumm, chief of staff for the research service, in a department-wide email that BuzzFeed obtained. The list of prohibited external communication included news releases, photos, fact sheets, news feeds and social media content.

But Reuters reported Tuesday afternoon that USDA officials said the guidance on public communication by ARS at least was sent in error. “This internal email was released without Departmental direction, and prior to Departmental guidance being issued,” the USDA said in a statement. “ARS will be providing updated direction to its staff.”

A source at the USDA’s Food and Nutrition Service, which oversees programs like the Supplemental Nutrition Program and WIC, said the service has also been told to stop all posting to social media, updating the website or sending any public messages, including press releases and email, until further notice.

Sean Spicer, the president’s press secretary, said during his daily briefing on Tuesday that he needed to look further into the whole matter before he could offer a comment.

Officials with the Trump transition team, however, defended the freezing of EPA grants and contracts as somewhat larger in scope than the acts of previous transitions, but similar in mission. Myron Ebell, who led President Donald Trump’s EPA transition process, said it was to “make sure nothing happens they don’t want to have happen.”

As for the communications freeze, sources on Capitol Hill said they are worried about the timing of the directive. Lawmakers routinely help constituents to interface with federal agencies, especially those that fall under the HHS umbrella. If officials who deal with Medicare and Medicaid policies aren’t allowed to talk to members of Congress, one Hill aide noted, it will be impossible to address constituent concerns with those programs.

Additionally, this year’s Affordable Care Act enrollment continues until Jan. 31 and runs largely through the Centers for Medicare & Medicaid Services, which falls under HHS. If constituents have questions about coverage options, the aide noted, the communications freeze may make it impossible to address those issues.

It may also impede current scientific research that depends on federal funding, advocates worry.

“Any effort to stop a scientific agency from responding to congressional, federal, state and local inquiries has a chilling effect,” said Ben Corb, director of public affairs at the American Society for Biochemistry and Molecular Biology. “We steadfastly believe peer-reviewed science should remain free of politicization, and we support the NIH [National Institutes of Health] and all federally funded scientific agencies in their efforts to continue on their missions without political interference.”

A former EPA official under the Obama administration told HuffPost that while “it is completely normal for incoming administrations to come in and take stock of what’s happening across an agency,” the Trump team’s moves so far are “extreme and very troubling, especially when it comes to both the grant freeze and the public communications.”

“When it comes to the grants freeze, this could be especially problematic at the state level. EPA sends a huge amount of its budget to the states, where it is ultimately spent,” said the former official. “That’s where you could ultimately see the most negative impacts, especially at times when states are already suffering budget challenges. Time will tell, but this is not a great start when it comes to supporting states or transparency and a commitment to sharing important information with the public.”

The story has been updated with comments from sources at NIH and the Food and Nutrition Service, a former EPA official, and the White House press secretary and with further detail on the situation at the Agricultural Research Service.

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