Protesters against the war in Iraq will assume today the mantle — if not the kaftans — of the radical generation before them who 40 years ago demonstrated against military involvement in Vietnam.

The march marking the fourth anniversary of the Iraq invasion begins near the Vietnam Veterans’ Memorial Wall in Washington and will follow the same route across the Potomac River to the Pentagon taken by the antiwar protesters in 1967.

Organisers say that then, as now, the war had reached a turning point with a majority of Americans opposing an escalating conflict. Opinion polls suggest that there is more support for bringing troops home from Iraq by the end of the year than there was for a swift withdrawal from Vietnam.

But, just as with the Vietnam War, Iraq is opening up fissures between the Democratic Party and grassroots activists. Hillary Clinton, the frontrunner for the 2008 Democratic presidential nomination, is being continually hounded by the party’s Left over her refusal to apologise for her Senate vote five years ago authorising military action in Iraq. Even Democrats with impeccable antiwar credentials are becoming the focus of protesters, who claim that the congressional leadership is failing to act on the mandate given to it in November’s mid-term elections to end America’s military entanglement in Iraq.

A peace camp has been set up outside the San Francisco home of Nancy Pelosi, the Speaker of the House of Representatives, while other leading Democrats have seen their Congressional offices occupied briefly by demonstrators.

The Democratic leadership, however, remains mindful of the lasting image for being weak on national security issues that was established in many voters’ minds during the Vietnam era and that helped Richard Nixon to win successive presidential elections.

While seeking to chip away at President Bush’s Iraq policy with legislation attaching conditions to war funding and setting a timeline for military withdrawals, the Democrats will do nothing that might leave them vulnerable to charges of undermining troops. Instead, they have seized on the scandal of poor conditions for injured war veterans at the Walter Reed Army Medical Centre as evidence that the Republicans are no longer the true champions of troops. Yesterday there were fresh disclosures about a VIP suite at the hospital that is usually open only to the likes of the President, Vice-President and foreign dignitaries.

The Democrats’ grudging support for a supplemental Bill worth another $124 billion (£64 billion) in funding continues to attract fury from activists, two of whom confronted Congressman David Obey in the corridors of Capitol Hill recently. He told them that the Democrats did not have the votes in both Houses of Congress to stop the funding, and were trying to make changes through other legislation. “You cannot end the war if you vote against the supplemental,” he shouted. “It’s time these idiot liberals understood that.” The exchange was filmed and swiftly appeared on the YouTube website, forcing an apology from Mr Obey.

Organisers of today’s antiwar march insist that there will be no repeat of the violent clashes with military police that marred the 1967 protest, even though a counter demonstration called the Gathering of Eagles is promising to protect the Vietnam Memorial from vandalism.

Instead, through YouTube and websites such as Moveon. org, which is helping to mobilise activists across America, they believe that they have much more potent weapons in their arsenal than those of their parents or grandparents who marched a generation before.

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