For one thing, they pointed out that Americans increasingly use mobile phones -- instead of home phones. And since mobile phone numbers are not generally available to poll-takers, a significant percentage of the population was not being polled.
Americans also increasingly screen their calls and are less likely to answer a call from an unknown caller.
Besides, many said that the turnout would be higher than in previous recent elections, and that the opinion polls were ill-equipped to anticipate these higher numbers of voters.
Patrick Basham studies American politics at the Cato Institute, a private policy center in Washington. He says it's time for Americans to stop complaining about polls. Basham says this time the opinion polls got it right.
"The artistry [involved in polling], whether it was intuitive or otherwise, was more accurate than most people [believed.] [The poll takers had to] devise or refine their models to account for the expected surge in voting, in particular among younger voters, and they clearly got it pretty right. The polls, even up to the end -- very few were outside the margin of error. And we had this apparent [conflict among some polls] simply because it was just such a close race," Basham says.
Basham says the problem may not lie with the polls but with popular perceptions ahead of the vote. The polls were predicting a close race, but the media outlets were full of stories suggesting Bush's challenger, Democratic Senator John Kerry, was surging and had taken the momentum.
"We have a very good example of how those who scream the loudest get the most attention. And the assumption has been that there is this large, anti-Bush sentiment -- and that's true. But of course how do you measure the pro-Bush sentiment? That's very hard to do when people aren't demonstrating, et cetera," Basham says.
In fact, Basham points to the most vocal of the Kerry supporters -- American youth -- as over-promising their participation in political process and under-performing on election day. He notes that turnout among young voters was relatively low and unchanged from the election in 2000.
Robert Spitzer, a professor of political science at Cortland campus of the State University of New York, agrees that the media may have overplayed Kerry's support and missed Bush's quieter, yet stronger support.
"The [voter] mobilization on the Bush side was quieter, it was more low-key, and partly that was by design, because the Republican organization was much more hierarchical, they don't talk to the press as much. They really wanted to operate below the radar screens of the media. And I think as a consequence, they went to some degree unnoticed by the media. And so the media tended to focus more on the mobilization effort on the Democratic or Kerry side. Both sides did a good job mobilizing their people, but the Republicans did a little better job," Spitzer says.
Despite their generally good performance before the election, poll takers erred badly on election day itself in so-called "exit polls" -- surveys taken of voters as they are leaving voting precincts to learn whom they chose and why. These polls are thought to be the most reliable because they deal not with a voter's intention, but with the actual vote.
This year the poll-takers ran into problems. "The New York Times" newspaper reports that it obtained an internal report by one of the major poll-takers which said questioners were deterred because they could not get close enough to voting precincts and, apparently, because those who had just voted for Bush were less open to interviews.
Whatever the reasons, the exit polls, for the first time, gave Kerry a lead over Bush -- and this time they were wrong.