The death of the 2,000th US soldier in Iraq is expected to trigger peace rallies in Washington and across America today as anti-war campaigners use the milestone to demand that the Bush Administration withdraws US troops.

Outside the White House, Cindy Sheehan, the peace activist whose 24-year-old son died in Iraq and who has become the most recognised face in America's anti-war movement, has promised to "symbolically die" over the coming days until she is arrested.

"What I think it’s going to take now is non-violent, peaceful civil disobedience all over the country," said Mrs Sheehan, who plans to lie down in the street opposite the White House today. She told supporters: "Go to your senators’ offices, to federal buildings. Sit down and say enough is enough. The killing has to stop sometime."

The call for protest was echoed by Move On, a coalition of anti-war and left-wing groups that has organised protests against the Bush Administration in recent years. Move On released a new television advert, asking "How Many More?", and has co-ordinated more than 1,000 vigils that are due to take place this evening.

The Answer coalition, an anti-war group that drew more than 100,000 protesters to a rally in Washington last month, said the 2,000th death showed that "Bush and Cheney are willing to fight this illegal war until the last drop of other people’s blood" and that "public opinion in the United States has decisively turned against the war in Iraq just as it turned against the war in Vietnam three decades ago."

The toll landmark was reached when Staff Sergeant George Alexander Jr., 34, of Killeen, Texas, died on Saturday of wounds sustained in an explosion in Samarra on October 17. His death was announced yesterday by the Department of Defence.

The news prompted a moment of silence in the Senate to remember the dead and a stream of statements from Democrat politicians, who criticised the Bush Administration's handling of the war.

"Our Armed Forces are serving ably in Iraq under enormously difficult circumstances, and the policy of our government must be worthy of their sacrifice. Unfortunately, it is not, and the American people know it," said Senator Edward Kennedy, of Massachussetts.

"Words of tribute are in order to honor the sacrifice of these brave men and women and their loved ones. But words are not enough. We owe them leadership and a clear strategy to bring our troops home with their mission truly accomplished," said Senator Dick Durbin, of Ilinois.

In a speech yesterday President Bush told a lunch for military wives that the American public should expect more casualties in the struggle against "as brutal an enemy as we have ever faced, unconstrained by any notion of common humanity and by the rules of warfare."

Today's protests and vigils come in what the American press has called "the darkest days" of the Bush White House.

Under the shadow of a falling approval rate, Mr Bush is struggling to nominate his former personal lawyer to the Supreme Court and is facing the possible criminal indictment of two of his most trusted advisers on charges of disclosing the identity of an undercover CIA agent, a federal offence.

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