A senior presidential aide violated federal law when he sent out a tweet calling for the defeat of a Republican member of Congress in a primary election. At least that’s the view of the US Office of Special Counsel, a watchdog agency within the US government that enforces the federal government’s civil service laws.

As White House Director of Social Media, Dan Scavino helps to manage the Trump administration’s social media presence. In April, he tweeted out an attack on Rep. Justin Amash, a libertarian-leaning Republican from Michigan who has frequently criticized Donald Trump:

.@realDonaldTrump is bringing auto plants & jobs back to Michigan. @justinamash is a big liability.#TrumpTrain, defeat him in primary. — Dan Scavino Jr. (@DanScavino) April 1, 2017

In a complaint to the OSC, the public interest group Citizens for Responsibility and Ethics in Washington (CREW) argued that this was a violation of the Hatch Act, a law that’s intended to prevent public officials from engaging in partisan politics.

Scavino made the tweet from his personal Twitter account, but CREW argued that didn’t matter: He listed his White House job in his Twitter bio, and his profile picture showed him standing in the Oval Office. That, CREW argued, made the tweet an official act as a White House official — a violation of federal law.

And now we know the federal official charged with enforcing the Hatch Act agrees. Ana Galindo-Marrone, chief of the OSC’s Hatch Act Unit, sent CREW a letter endorsing this conclusion.

“OSC has concluded that this activity violated the Hatch Act,” she wrote. “Accordingly, we issued Mr. Scavino a warning letter” and provided Scavino with training on the law. She warned that he could face stiffer disciplinary action if he violates the Hatch Act again. Potential penalties could include loss of his job and up to $1,000 in fines.

Big win for CREW! Dan Scavino reprimanded for Hatch Act violation! pic.twitter.com/noOXeUGOIk — Citizens for Ethics (@CREWcrew) June 9, 2017

This isn’t the first time the White House has run afoul of federal ethics guidelines. In February, White House spokesperson Kellyanne Conway was reprimanded by the Office of Government Ethics for promoting products endorsed by President Trump’s daughter, Ivanka.