Lieberman's attack on anti-war rivals shows deep divide within Democrats

The deep divisions on Iraq among the Democratic presidential contenders burst into the open yesterday when the senator Joseph Lieberman, a strong supporter of the conflict, accused his more critical rivals "of not knowing a just war when they see it".

Mr Lieberman said the Bush administration had failed to draw up adequate plans for the aftermath of the war and had not moved quickly enough to secure Saddam Hussein's suspected illegal weapons facilities. But his most significant words were aimed at other Democrats, not only the insurgent Howard Dean but those, such as John Kerry of Massachusetts, who, having backed a congressional resolution sanctioning force, is challenging the premise on which the war was fought. "Congress did the right thing in authorising the war," Mr Lieberman said, just 24 hours after Bob Graham, the Florida senator also seeking the Democratic nomination, suggested for the first time that Mr Bush deserved to be impeached because he had misled Americans about the threat posed by Saddam.

Referring to Bill Clinton's unsuccessful impeachment for obstructing justice in the Monica Lewinsky affair, Mr Graham said that Mr Bush's behaviour to justify an invasion was "much more serious in terms of dereliction of duty". He was reacting to remarks made by Paul Wolfowitz, the Deputy Defence Secretary and a leading hawk, who said on Sunday that the US invasion had been justified even though intelligence data was "inherently murky".

With the exception of Mr Graham and Mr Dean, the main Democratic contenders are finding it hard to explain how they voted for the use of force but are now challenging Mr Bush. Democratic strategists also fear that while an anti-war stance may go down well with the party faithful in the primaries, it may be a disaster in the general election.

Mr Dean's popularity is surging but he is also the candidate the Bush campaign would most relish taking on in autumn 2004. If nominated, he could meet the same fate as George McGovern in 1972 who, at the height of the Vietman war, was labelled by the Nixon campaign as unpatriotic - and lost by a landslide.