The U.S. Office of Special Counsel has opened a case file on Interior Secretary Ryan Zinke after receiving a complaint alleging he may have potentially violated the Hatch Act when he posted a photo of himself wearing a pair of "Make America Great Again" socks on social media.

"I can confirm that OSC received the complaint and has opened a case file," Office of Special Counsel spokesman Zachary Kurz told the Washington Examiner. "However, I'm unable to comment on or confirm whether an investigation has been opened."

The case file was first reported by CNN.

The complaint, made by Campaign for Accountability in June, came after Zinke donned a pair of socks emblazoned with a President Trump-like figure and Trump's 2016 campaign slogan when he attended the Western Governors’ Association’s annual meeting in South Dakota, also in June. Zinke then posted an image of the socks on Twitter, before deleting the tweet and writing an apology missive on the social media platform.

"Earlier I tweeted a pic of my new socks not realizing it had what could be viewed as a political slogan," Zinke wrote. "I’ve deleted it and apologize for the mistake. I remain excited about all the incredible policy work POTUS is doing."

His apology tweet has also been scrubbed from his profile.

The Interior Department did not immediately respond to the Washington Examiner's request for comment .

The Hatch Act prevents Cabinet-level officials from taking part in political activity, including wearing any item of clothing that could been construed as a campaign endorsement.

This is the second complaint Campaign for Accountability has made against Zinke.

The Office of Special Counsel cleared Zinke in May of allegations made in the first complaint, finding no evidence that he "gave a political speech or otherwise engaged in political activity" during an event with the Las Vegas Golden Knights hockey team in June 2017.