Democratic congressional candidate Mark Critz attended the grand opening of the office on East Chestnut Street in the city of Washington.
Critz also received the endorsement Wednesday of the United Mine Workers of America in his race to fill the seat of the late Rep. John Murtha.
Critz was a longtime aide to Murtha, who died Feb. 8.
Former House Speak Newt Gingrich is planning to attend a reception for Republican candidate Tim Burns on Thursday in Latrobe.
The May 18 special election is one of the most closely watched House races in the country.