The angry mother of a fallen U.S. soldier staged a protest near President Bush's ranch Saturday, demanding an accounting from Bush of how he has conducted the war in Iraq.

Supported by more than 50 demonstrators who chanted, "W. killed her son!" Cindy Sheehan (search) told reporters: "I want to ask the president, `Why did you kill my son? What did my son die for?" her voice cracking with emotion. "Last week, you said my son died for a noble cause' and I want to ask him what that noble cause is?"

Sheehan, 48, didn't get to see Bush, but did talk about 45 minutes with National Security Adviser Steve Hadley (search) and Deputy White House Chief of Staff Joe Hagin (search), who went out to hear her concerns.

Appreciative of their attention, yet undaunted, Sheehan said she planned to continue her roadside vigil, except for a few breaks, until she gets to talk to Bush. Her son, Casey, 24, was killed in Sadr City, Iraq, on April 4, 2004. He was an Army specialist, a Humvee mechanic.

"They (the advisers) said we are in Iraq because they believed Saddam Hussein had weapons of mass destruction, that the world's a better place with Saddam gone and that we're making the world a safer place with what we're doing over there," Sheehan said in a telephone interview after the meeting.

"They were very respectful. They were nice men. I told them Iraq was not a threat to the United States and that now people are dead for nothing. I told them I wouldn't leave until I talked to George Bush."

She said Hagin told her, "I want to assure you that he (Bush) really does care."

"And I said if he does care, why doesn't he come out and talk to me."

Sheehan arrived in Crawford aboard a bus painted red, white and blue and emblazoned with the words, "Impeachment Tour." Sheehan, from Vacaville, Calif., had been attending a Veterans for Peace (search) convention in Dallas.

The bus, trailed by about 20 cars of protesters and reporters, drove at about 15 mph toward Bush's ranch. After several miles, they parked the vehicles and began to march, in stifling heat, farther down the narrow country road.

Flanked by miles of pasture, Sheehan spoke with reporters while clutching two photographs, one of her son in uniform, and the other, a baby picture, when he was seven months old.

She said she decided to come to Crawford a few days ago after Bush said that fallen U.S. troops had died for a noble cause and that the mission must be completed.

White House Spokesman Trent Duffy said response that Bush also wants the troops to return home safely.

"Many of the hundreds of families the president has met with know their loved one died for a noble cause and that the best way to honor their sacrifice is to complete the mission," Duffy said.

"It is a message the president has heard time and again from those he has met with and comforted. Like all Americans, he wants the troops home as soon as possible."

The group marched about a half-mile before local law enforcement officials stopped them at a bend in the road, still four to five miles from the ranch's entrance. Capt. Kenneth Vanek of the McLennan County Sheriff's Office said the group was stopped because some marchers ignored instructions to walk in the ditch beside the road, not on the road.

"If they won't cooperate, we won't," Vanek said.