John Murtha's widow is endorsing an aide to the late congressman in his bid to fill Murtha's former House seat.
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.
A special election to fill the vacancy will be held as part of Pennsylvania's May 18 primary. 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 businessman Tim Burns.
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