From USPS News Link:
If you have a photo in your workspace of a candidate for president of the United States, you may be violating federal law.
The Hatch Act prohibits postal employees from engaging in political activity while on duty in any government office, while wearing an official uniform or while using a government vehicle. Among other restrictions, postal employees also may not wear items â€” such as shirts, hats or buttons â€” displaying the name or likeness of a candidate or political party while at work, nor may they post pictures of political candidates in their workspace.
On April 4, President Barack Obama announced his candidacy for re-election. As a result, only official photographs of the president can be displayed in USPS workspaces. Official photographs include the traditional portrait photograph of the president displayed in federal buildings, and photographs of the president conducting official business. News clippings and pictures from the Internet are not official photographs.
Employees may display photographs of President Obama or any other political candidate if the picture is of the employee and the political candidate, if it was taken at a non-political event such as a wedding or school reunion, and the photo was on display prior to the candidacy.
Photos of Mitt Romney, the former governor of Massachusetts, also must be removed from workspaces. Romney announced his candidacy for president April 11.
Violations of the Hatch Act carry serious penalties â€” including possible termination. For more information about the Hatch Act, contact USPS ethics officials at 202-268-6346 or send an email to firstname.lastname@example.org.