Washington (CNN) Now that President Donald Trump is officially running for re-election, federal workers need to leave their Make America Great Again hats at home or risk violating election law, the Office of Special Counsel said Monday.

The Office of Special Counsel is the federal agency responsible for enforcing the Hatch Act, which prohibits federal employees from engaging in politics while on the job, in uniform, or using government resources. It released a new set of guidelines Monday that advises federal employees on what they can and can't do. (OSC is not related to the investigation of Justice Department special counsel Robert Mueller.)

"This prohibition is broad and encompasses more than displays or communications (including in-person and via email or social media) that expressly advocate for or against President Trump's reelection," the guidance states.

Until now, federal employees were free to bring memorabilia from his 2016 campaign to the office, or hang non-official photos of Trump in their offices -- so long as they did not indicate support "for or against his re-election in 2020," according to a OSC determination last year.

But that changed with the announcement of a campaign manager for Trump's re-election bid and restrictions now apply.

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