Joyce Murtha says Mark Critz is "the most qualified and knowledgeable candidate in the field."
Critz resigned as district director in Murtha's office on Monday and announced his plan to run in a special election to fill the seat temporarily as well as the Democratic primary for another term.
Murtha died Feb. 8 following complications from gallbladder surgery.
Democrats running include former Pennsylvania treasurer Barbara Hafer, former lieutenant governor Mark Singel and Cambria County Controller Ed Cernic Jr.
Prospective Republican candidates include William Russell, who unsuccessfully challenged Murtha in 2008, and Eighty Four businessman Tim Burns.
