Opinion polls play a significant part of US politics, particularly for a presidential election. They tell us what people believe, what they think about a topic and – significantly – how they plan to act.

The media use opinion polls as opportunities to create stories about how well a candidate is fairing during an election campaign. Even if a candidate’s poll rating drops by a percentage point, you can almost guarantee a TV broadcaster dedicating a large section of their coverage as to why and how this happened.

They’re early indicators to see which candidate is likely to emerge victorious, but they shouldn’t be taken for as the gospel truth. For example, polls predicted Republican Thomas E. Dewey was set to win the 1948 presidential election against Democrat Harry S. Truman. Newspapers went to print reporting Dewey had won, relying on the polls, but were left red-faced when Truman became the 31st President of the United States.

Nevertheless, results of polls determine where future campaign monies are to be spent and where candidates’ efforts will be concentrated until the end of the campaign.

Have a look at the interactive graph below to see how Obama and Romney have done in the polls leading up to the election.

Source: RealClearPolitics – average results from Gallup, Rasmussen Reports, AP, CNN, NY Times and other pollsters.