A convention bounce, in U.S. politics, is the favorable poll results that usually come after the major political parties have had their national conventions. Democrats and Republicans both have a national convention to nominate a candidate for president every four years. During this time, a great deal of media attention is focused on the parties and usually includes a favorable increase in the polls.
The Republican National Convention and Democratic National Convention are never held at the same times, therefore the coverage each gets is nearly exclusive. This coverage usually leads pollsters to find the candidate representing that party gains in popularity. Usually, this happens in the days after the convention. Thus, it is known as a convention bounce.
Due to the fact that the conventions are held at different times, one candidate usually receives a convention bounce first. Sometimes, this bounce can be impressive, as many as 10 percentage points in the polls. These bounces are normally cause for a great deal of analysis and excitement, at least from within the campaigns themselves.
However, because the other party's convention follows soon after, the first convention bounce may be short lived. This is because the other candidate is likely also going to receive a convention bounce. After the second convention, the polls usually sort themselves out going into the final weeks of the campaign.
Some political experts say a convention bounce does not matter, that it is based entirely on an emotional response. The political parties spend millions of dollars to put on a good show, usually geared toward the millions of television viewers watching at home. The show quality of the convention may be what is mainly responsible for the convention bounce. It could be that the party with the better "show" gets the greater bounce.
Some have also questioned the value of the convention bounce, saying that either the bounces equalize, or they are otherwise temporary phenomena. However, in some cases, a convention bounce may give a candidate an edge the other candidate is never able to overcome. In the 1992 election, Bill Clinton received just such a bounce, between 15 and 20 points, coming out of the Democratic National Convention. The incumbent president, George H.W. Bush, was never able to recover. Thus, while the convention bounce may be harmless in most cases, there are times when it can be very dangerous to the opposing candidate and therefore must always be taken seriously.