On February 6, 2003, just before the war against Iraq began, a Time/CNN/Harris Interactive poll found that a large majority of Republicans, fully 82 percent, thought Saddam Hussein was then providing assistance to Osama bin Laden's al-Qaeda terrorist network. Though still a high percentage, fewer Democrats, 68 percent, and somewhat fewer Independents, 77 percent, also thought that Saddam provided assistance.

As months went by, aggregate public opinion began to change, but in contrast to the overall trend, Republicans' perceptions remained stable while those of Democrats changed substantially. Every two months from June 2003 to April 2004, a question with identical wording was asked by Harris, concerning whether clear evidence of Iraq in support of al-Qaeda had been found. As shown in Figure 1, during the entire period a large majority of Republicans (around 74 percent) consistently responded that they thought clear evidence had been found (70 percent in June 2003, and 78 percent in April 2004), while this percentage among the Democrats dropped from 58 percent on June 2003 to only 39 percent on April 2004, close to a twenty-percentage-point change. Since the proportion of Republicans convinced that there was clear evidence stayed roughly the same, their level of misperception was twice that among Democrats in the latter poll. Independents, presumably unaffected by partisan concerns and conflict, were closer in their views to the Democrats.

A more recent poll, conducted by ABC News in March 2005, showed that these differences continued among the partisan subgroups: 34 percent of Republicans, compared to only 13 percent of Democrats, thought solid evidence had been found that Iraq provided direct support to al-Qaeda before the war.

As for the connection between Iraq and WMDs, a substantial proportion of Republicans continued to differ from Democrats in their perceptions. Again, at six different time-points, an identical question was asked by the same survey organization, Harris Interactive, concerning the belief that Iraq had WMDs when the war began ("Do you believe that Iraq actually had weapons of mass destruction when the war began or not?"). As Figure 2 indicates, during the entire period an even larger majority of Republicans than believed in evidence of an Iraq/al-Qaeda connection responded that Iraq had WMDs when the war began (86 percent in June 2003 and 80 percent in April 2004), while the proportion of Democrats believing this decreased from 69 percent in June 2003 to only 36 percent in April 2004. Thus, there was more than a forty-percentage-point difference in the proportion of Republicans versus Democrats who believed Iraq had WMDs when the war began. Indeed, more than twice the percentage of Republicans than of Democrats believed this. Independents, for the most part, fell largely between Democrats and Republicans in this case, though they moved closer to the Democrats after the first poll in the series.

The March 2005 ABC News poll again showed that this pattern continued, with 79 percent of Republicans, compared with only 37 percent of Democrats, still thinking that Iraq had WMDs shortly before the war.

As with the matter of a link between Iraq and al-Qaeda, Time/CNN/Harris also periodically asked a "clear evidence" question regarding WMDs. The responses showed that, once again, the perceptions of all three partisan subgroups changed over time, with a decline in the percentage of each group perceiving that clear evidence had been found. As shown in Figure 3, in June 2003, 48 percent of Republicans believed clear evidence of WMDs had been found in Iraq. Asked again in August, October, and December, and in February and April of the following year, these views slipped to the 30 percent level. This drop was more rapid and sharper for Democrats; those who believed such evidence had been found fell from 35 percent on June 2003 to 10 percent in 2004. Still, in April 2004, three times the proportion of Republicans (33 percent) compared to Democrats (11 percent, and nearly the same percentage of Independents, 14 percent), held this view.