By Jonathan Marcus BBC US affairs specialist

Democrats question Bush's strength on foreign policy

A leading contender for the US Democratic Party's nomination in next year's presidential race has assailed President Bush, declaring he misled Americans and waged a war on questionable intelligence.

John Kerry, a senator from Massachusetts, is widely seen as a Democratic front-runner and, as a Vietnam veteran, has a powerful moral voice on issues of war and peace.

His comments reflect a growing realisation in the Democratic camp that President Bush may be vulnerable on his handling of foreign policy.

The war in Iraq divided the Democrats and appeared to strengthen President Bush's strong image in foreign policy.

Since then the Democrats' nine Presidential hopefuls have been jockeying for position amongst themselves - but they have also eagerly tried to find a chink in the President's armour.

Senator John Kerry's powerful condemnation of Mr Bush signals that he for one believes the Bush administration may indeed be vulnerable on what up to now has been its safest political terrain - national security.

Senator Kerry is not alone.

Insider view

Another Democratic contender, the former Vermont Governor Howard Dean, has begun television advertising in Iowa, where the Democratic hopefuls will face their first real test in a caucus - a kind of selection meeting - next January .

In the advert Dean opens with the words: "It's time for the truth, because the truth is that George Bush's foreign policy isn't making us safer."

Democrat candidates focus on national security issues

So are Mr Kerry and Mr Dean right? Is the president vulnerable on defence and foreign policy?

All the signs are that this is still one of the president's strongest cards, and the Democrats are generally seen as being weak on national security.

But with continuing Congressional investigations about the intelligence that justified the Iraq war; with US troops taking almost daily casualties in Iraq; and with little sign of real progress in Afghanistan, some Democratic strategists believe that this issue could move in their favour.