Some focused their attacks on the Bush doctrine of pre-emption, repudiating the decision to invade a country that had not attacked the US first.
Others, who supported the effort to remove Saddam Hussein, defended the justification for war while criticising the post-war occupation and the failure to find weapons of mass destruction.
All nine of the Democratic candidates for president derided Bush on Iraq for various reasons.
Massachusetts Senator John Kerry, who effectively secured the nomination by dominating the Super Tuesday primaries, said during a recent speech that Iraq is in "disarray".
Yet, despite such criticism, few experts in Washington predict any serious short-term changes in the US position on Iraq if Kerry wins the election in November.
"I don’t think the stakes are immediately dramatic," said Jay Farrar, vice-president of external affairs at the Centre for Strategic International Studies, a Washington think tank.
Anti-Iraq-war candidate Howard
Dean is now out of the race
"If a Democrat took the White House, I don’t think that you would see an immediate and dramatic change [in Iraq]."
Many pundits credited Howard Dean with galvanising the Democratic Party with his fiery opposition to the Iraq war, a message co-opted by Kerry and the other candidates.
The notion, however, that a Democratic president would be able or willing to quickly reverse course in Iraq is unrealistic, Farrar said.
"[The Democrat candidates] give you the impression that: 'If we were in the White House come January  things would change dramatically','" he said. "It's not that simple."
Even some Democratic activists admit that a Kerry victory would not precipitate the kind of drastic changes in Iraq that some anti-war voters on the left might expect with a Democrat in charge of US foreign policy.
"I think that the honest answer would be that there would not be that much difference in the short term," said Will Marshall, president of the Progressive Policy Institute, a centrist Democratic organisation in Washington.
It is unlikely that Democrat John
Kerry would make many changes
The prevailing notion in Washington among both Democrats and Republicans is that the US must stay the course in Iraq to ensure a successful transition to some form of democracy, regardless of any debate over the justification of pre-emptive war.
Maintaining that commitment would dissuade Kerry from changing the US strategy in Iraq too hard or too fast, experts said.
Analysts caution that it is still too early to predict what Iraq will look like next year or how successful the planned transfer of power to the Iraqi Governing Council will be.
The political developments over the next 10 months will shape the direction of US policy in Iraq regardless of who wins the presidential election, they said.
"At that point, the situation in Iraq is bound to look different than it is now and [the next administration] will be reacting to that situation," said Gideon Rose, managing editor of Foreign Affairs, a bi-monthly journal published by the Council on Foreign Relations.
If Democrats regained control of the executive branch, any changes in Iraq would unfold gradually over the course of 2005, and would most likely entail a greater role for the UN and increased participation from the international community, several experts said.
"I think a Democratic administration would be willing to give up more control to the UN and that would convince more nations to send troops," said Lawrence Korb, a former assistant secretary of defence during the Reagan administration and currently a senior fellow at the Centre for American Progress, a liberal advocacy group.
"A Democratic administration would be willing to give up more control to the UN"
Centre for American Progress
Kerry himself has been vague about what specific changes he would make in the US presence in Iraq, but said the UN should assume control of the reconstruction effort and that the military force structure must be internationalised.
Kerry’s staff at his national headquarters in Washington could not be reached for comment, but his campaign website offers a general outline of his proposals on Iraq.
While the senator’s plan would transfer responsibility for Iraq to the UN, a description on his website said, "This cannot happen overnight and that the CPA [Coalition Provisional Authority] will have a key role in ensuring a smooth turnover."
The website also said Kerry would "eliminate Bush’s discriminatory contracting procedures and offer a genuine partnership of responsibility in return for a genuine partnership of burden-sharing – troops and money".
Despite the Bush administration’s initial reluctance to give the UN a greater role in Iraq’s reconstruction, it has attempted to bring the UN into the fold in recent weeks and has tried to mend rifts with its European allies who opposed the war.
Plans for an early US withdrawal
from Iraq remain off the agenda
Some experts, however, said the Democrats would have an easier time convincing the international community to provide more assistance.
"[Democrats] don’t carry the baggage that this administration has," Farrar said.
The most unlikely scenario in Iraq, regardless of which political party controls the White House, would be an abrupt withdrawal of US forces anytime soon, experts said.
"The dangers of pulling out of Iraq rapidly now are so obvious that it is highly unlikely that anyone would do that," Rose said.
Korb said whatever opposition to the war might linger in Democratic circles, the consequences of failure would override those sentiments.
“There’s no way the United States, even if Ralph Nader is running the country, can have an unstable Iraq considering where we are now,” he said.