WASHINGTON -- U.S. Rep. John Murtha, D-Johnstown, a decorated Marine Corps Vietnam veteran who is among the most hawkish Democrats in Congress, said yesterday the United States should begin withdrawing troops from Iraq immediately.

"We have become a catalyst for violence," Mr. Murtha told a news conference. "Our military has done everything that has been asked of them, the U.S. can not accomplish anything further militarily. It is time to bring them home."

A dozen Republicans hastily put together a press conference where some accused Mr. Murtha, 73, and the Democratic Party of "waving a flag of surrender" and undermining U.S. troops.

Despite divisions over the war within the Democratic caucus, several Democrats said Mr. Murtha's position change could create a profound shift within their party, particularly among those who feared speaking out against the war.

In his announcement, Mr. Murtha said he had weighed the risks of an overstretched military, an "out of control" deficit and the situation on the ground in Iraq, which he believes is getting worse with each day. He noted only half of the $18 billion Congress allocated for Iraq's reconstruction has been spent and that unemployment in Iraq is above 40 percent. His many visits to Iraq, he said, had convinced him that Iraqis want U.S. soldiers to leave.

"Instead of attacks going down over time and with the addition of more troops, attacks have grown dramatically," Mr. Murtha said. "I have concluded that the presence of U.S. troops is impeding this progress."

Mr. Murtha proposed withdrawing U.S. troops immediately -- a process he believes could be completed within six months -- and said the U.S. should continue its efforts to stabilize and secure Iraq diplomatically. The visible withdrawal of troops, he said, would assure Iraqis who will participate in elections in mid-December that their nation is "free from U.S. occupation."

He said the coalition forces should keep "a quick-reaction force" in the region and an "over-the-horizon presence" of Marines who could go back into Iraq in emergency situations.

Mr. Murtha, who is the ranking member of the House Appropriations Committee subcommittee on defense, was clearly anticipating the criticism that came within minutes of his announcement. Asked about President Bush and Vice President Dick Cheney's contention that those who criticize the war efforts and the pre-war intelligence are irresponsible, Mr. Murtha had his own rapid-fire response.

"I like guys who've never been [in combat] that criticize us who've been there," he said.

"I like guys who got five deferments," Mr. Murtha said, referring to Mr. Cheney's five deferments during the Vietnam War, "and then don't like to hear suggestions about what needs to be done.... Lashing out at critics doesn't help a bit. You've got to change the policy."

The reaction from Republicans on Capitol Hill to Mr. Murtha's withdrawal plan was swift and in some cases fierce.

House Speaker Dennis Hastert, R-Ill., said the idea was "the highest insult to the brave men and women serving overseas."

U.S. Rep. Geoff Davis, R-Ky., who served in the Army, referred to Mr. Murtha's comments as "shameful statements," and linked them to the call by al-Qaida leaders for expelling Americans from Iraq.

U.S. Rep. Melissa Hart, R-Bradford Woods, said she did not think Mr. Murtha's military service should add weight to his comments.

"He's a member of Congress just like everyone else," Ms. Hart said. "As far as I know, he's not been intimately involved in the strategy in Iraq and has any intimate knowledge about the training of the Iraqi security forces."

White House spokesman Scott McClellan, travelling with the president in the Far East, said it was "baffling that [Murtha] is endorsing the policy positions of Michael Moore and the extreme liberal wing of the Democratic party. The eve of an historic democratic election in Iraq is not the time to surrender to the terrorists. After seeing his statement, we remain baffled -- nowhere does he explain how retreating from Iraq makes America safer."

But House Armed Services Chairman Duncan Hunter, R-Calif., sought to distinguish his disagreement with Mr. Murtha's position from his admiration for the Pennsylvania congressman's long military service. He said he some Democrats were looking at the political horizon, "but not John."

Mr. Hunter said the departure of U.S. troops from Iraq should be based solely on the assessment of commanders on the ground on whether "the Iraqi military has stood up with sufficient maturity to handle their security responsibilities."

Mr. Murtha got a standing ovation from his own party when he announced his decision. U.S. Rep. Mike Doyle, D-Swissvale, said Mr. Murtha brought tears to the eyes of many of his colleagues as he described his weekly visits to soldiers at Washington area military hospitals including Walter Reed, and Mr. Murtha choked up describing the hardships of some of those soldiers during his press conference.

"It's a major turning point," said Mr. Doyle, who has opposed the war since the beginning. "This is not a liberal Democrat or a peacenik -- this is a hawk.... I think he did more this morning in the caucus to unify us than I've seen in my 11 years in Congress.

"[Mr. Murtha] has no peers in the caucus on matters of defense and when he's saying it's time to do this, people pay attention."