Another reason is that Murtha has become out of touch with his district and has been voting as a liberal instead of the conservative he claims back home to be. In particular:
Murtha voted against the Real ID Act, to establish and rapidly implement regulations for State driver's license and identification document security standards, to prevent terrorists from abusing the asylum laws of the United States, to unify terrorism-related grounds for inadmissibility and removal, and to ensure expeditious construction of the San Diego border fence.
Murtha was one of only 58 Representatives to vote against allowing federal courts to review the Terri Schiavo case while she was being starved to death.
Murtha voted to use taxpayer dollars to finance research that destroys embryos for their stem cells.
Murtha voted against the USA PATRIOT and Terrorism Prevention Reauthorization Act.
Murtha voted against the Gasoline for America's Security Act, to expedite the construction of new oil refineries in the United States and implement penalties to prevent gasoline suppliers from overcharging consumers.
No argument here, Boss! :-)