First Potomac Realty Trust filed a bid protest against the GSA, which leases roughly 175k SF from it for the Department of Homeland Security and the Department of Justice. The GSA has been leasing space at First Potomac's Prosperity Metro Plaza (pictured) since 2004, but could be looking for alternative locations to house the agencies. In November, GSA issued a tentative pre-solicitation for 104k SF, the Washington Business Journal reports, but hasn't announced a formal request for proposals. First Potomac is getting a head start before a formal RFP is issued, arguing that vacancy rates in Northern Virginia are high because of sluggish leasing from federal agencies and private companies. No word on whether first Potomac is protesting a move by the DHS or the Justice Department's DEA. A decision is expected around late August. [WBJ]