@Cruiser The “vast majority”? I don’t think so. “Majority” means “more than 50%.” So “vast majority” must mean something like “more than 75%” (if we’re being generous). At no point prior to the invasion was there more than 75% support for the war. In fact, the only point at which support was that high was May of 2003 (two months after the initial invasion). This was shortly after Saddam had been deposed and his statue torn down. So Americans were riding high on short-term success (and probably would have felt silly expressing distaste for the war so soon after it had begun and so close to such a large propaganda victory). But this was the only high point, and support went into a rapid free fall in the months after.
Prior to the invasion, however, we see a much different story. In January of 2003, only 31% of Americans supported a unilateral invasion. By February, the number had only increased to 37% despite Colin Powell’s infamous speech before the UN and the rise in Bush’s approval rating following his State of the Union address. That’s well below a majority, and nowhere close to a vast majority. Even worse, there was greater support for removing Saddam in the February prior to September 11th, 2001 than there was two years later in February of 2003. Back in February of 2001, 52% of Americans supported the use of American troops to depose Saddam Hussein.
That last number is slightly misleading. Polls at the time weren’t distinguishing between a unilateral invasion and a UN-supported one. And indeed, the polls just prior to the 2003 invasion revealed that Americans would have been much more supportive of the Iraq War had it been undertaken with international support (60% of Americans would have supported the war if the international community agreed that it was absolutely necessary). But their support was conditional, and that condition was never met. It is therefore probably safe to conclude that the 52% who supported using American troops to depose Saddam in February of 2001 were assuming international support and UN approval. That would mean there was consistent support for international action ranging from 52–60% (still not a “vast majority,” but at least a majority), but there was never widespread support for a unilateral invasion.