U.S. Democratic Congressman John Murtha, an influential critic of the Iraq War, died Monday. He was 77. (Cheryl Senter/Associated Press)

U.S. Democratic Representative John Murtha, a retired Marine Corps officer who became the first Vietnam War combat veteran elected to Congress and was later an outspoken and influential critic of the Iraq War, died Monday. He was 77.

The Pennsylvania Democrat had been suffering complications from gallbladder surgery. He died at the Virginia Hospital Center, spokesman Matthew Mazonkey said.

Murtha was an officer in the Marine Reserves when he was elected in 1974. Ethical questions often shadowed his congressional service, but he was best known for being among the most hawkish Democrats in Congress. He wielded considerable clout for two decades as the ranking Democrat on the House subcommittee that oversees Pentagon spending.

Murtha voted in 2002 to authorize President George W. Bush to use military force in Iraq, but his growing frustration over the administration's handling of the war prompted him in November 2005 to call for an immediate withdrawal of U.S. troops.

"The war in Iraq is not going as advertised. It is a flawed policy wrapped in illusion," he said.

Murtha's criticism of the Iraq war intensified in 2006, when he accused Marines of murdering Iraqi civilians "in cold blood" at Haditha, Iraq, after one Marine died and two were wounded by a roadside bomb.

Critics said Murtha unfairly held the Marines responsible before an investigation was concluded and fuelled enemy retaliation. Murtha said that the war couldn't be won militarily and that such incidents dimmed the prospect of a political solution.

In 2008, the Republican Party used Murtha's words against him in TV ads aired less than a month before the election. The ads cited his criticism of the Haditha incident, as well as his comment about "racist" voting tendencies of many western Pennsylvania residents.

Still, Murtha handily won his 18th full term.