In today's Washington Post, Sen. Ted Kennedy summarizes how Bush misled us into war with Iraq. You should read the whole thing, but this paragraph sums it up nicely:

Hussein's brutal regime was not an adequate justification for war, and the administration did not seriously try to make it one until long after the war began and all the false justifications began to fall apart. There was no imminent threat. Hussein had no nuclear weapons, no arsenals of chemical or biological weapons, no connection to Sept. 11 and no plausible link to al Qaeda. We never should have gone to war for ideological reasons driven by politics and based on manipulated intelligence.

Democrats need to say exactly this every time the issue of Iraq comes up.