There is a difference between believing that Saddam could be a potential threat if left unchecked and launching an all-out preemptive war. This article describes the dilemma the Democrats were in:

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A few times. … It was a very hard vote, because he could see the arguments, both directions, as to whether you vote yes or no on the resolution.

He would have preferred, like a lot of other people, the resolution that Joe Biden and Richard Lugar had come up with, which would have slowed the rush to war while putting the authority behind the president to get U.N. inspectors back in, to make sure Saddam Hussein couldn't use WMD. That was the point of the resolution.

The Bush administration wanted something more than that. They wanted something without any strings attached, so they could just go to war. John was [not] comfortable with it. Democrats were not comfortable with that, because they didn't want Bush just going to war unilaterally. They felt that was risky. John definitely was unhappy with that, and expressed it.

He'd been boxed. The Bush administration had chosen to box him and all the other Senate Democrats. "You either vote with us, in which case, you're responsible for it, too -- and we're going to do whatever the heck we please -- or you vote against us, and allow Saddam Hussein to be not held accountable. The president's position will be weakened, the United States' authority will be weaker in dealing with the rest of the world, and you not having stood up for American strength." …

The vote was designed to be an impossible vote for someone like John Kerry. That's why the Bush administration insisted on making the vote that way. It's a vote either to support the president, or undermine the president as the president's trying to deal with weapons of mass destruction that may be in the hands of an evil dictator.

John Kerry was not going to vote to undermine the president when the president was being directed to go the U.N. Remember, President Bush didn't even want to go to the U.N. There was a question of even going back to the U.N. to get inspectors back in. So it was a way of pushing it in the right direction, and hoping that the Bush administration would then do the right thing.

You're not given the choice of being 100 percent on these issues. You're not given the choice of doing exactly the way you would want to do it, when you're a senator. … As a senator, you're often forced to vote between two very difficult propositions, neither of which may be attractive. This vote was designed to be as unattractive, ugly, unpleasant, difficult, horrible, and damaging as possible by the Bush administration for Democrats, and in particular, any Democrat running for president. That was the point. That was the intention. It was designed to be a wedge vote, separating a John Kerry, for instance, from his natural constituents. …


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http://www.pbs.org/wgbh/pages/frontl...erry/iraq.html

North Korea is a bigger threat than Iraq. China is a threat. Iran is a threat. There is no way we can afford to launch a full-scale war against all of those countries. Nor would it be prudent.

The fact of the matter is that Bush undermined the credibility of the U.N. inspectors who reported that there were no WMDs in Iraq. Then the Bush administration backed the Democrats into a corner with a no-win vote. It was a slick poltical move, but it's cost this country hundreds of billions that could have been used to fight real terrorists, in addition to costing thousands of American soldiers their lives. The fact is that the President put the interests of the big oil companies who had sponsored his presidency above the interests of the American people and American security.