Editor's Note: Harvard Business School professor John Quelch writes a blog on marketing issues, called Marketing Know: How, for Harvard Business Online . It is reprinted on HBS Working Knowledge .

For all the coverage of the Presidential primaries, only half of eligible voters will likely cast ballots in November. While 20 percent of U.S. adults are political junkies, the rest can't spare the time, don't think their vote will matter, see no important differences among the candidates, or are turned off by the electoral process and candidates' campaign tactics.

They are the "vanishing voters" of U.S. politics. There are 5 structural reasons why this is the case.

In U.S. general elections, voters usually see only 2 viable candidates on the ballot. That's one reason turnout is low. In any other product category, there are many more choices. As a result, consumer interest—and consumption—is higher. In representative democracies, the consumer has to live with the majority decision. That also dampens enthusiasm. Not so in commerce. You can buy or own whichever brand, or suite of brands, you wish. In U.S. politics, citizens vote on a specified date once every 2, 4, or 6 years. Maybe they have to register in advance, wait in line at the polling station, and use an out-of-date polling machine to do so. The commercial marketplace is much more convenient. Consumers can cast their votes at millions of points-of-purchase every day. Some politicians understand that Branding 101 requires the development of a distinctive, appealing message, delivered consistently over time. But politicians can't win by targeting a single niche segment. They have to win a majority on election day, and doing so often means parsing words, trying to have it both ways, and allegedly flip-flopping on issues. In addition, the winner-takes-all system often leads candidates to desperate tactics such as negative advertising to tear down their opponents rather than promoting their own virtues. Citizens can be forgiven for being cynical. A final reason for consumer indifference to politics may be the effectiveness of commercial marketing. Most consumers have stronger relationships with brands like Starbucks (the "third place" after home and work) than with their elected representatives or the umbrella political brands, Democrat or Republican.

Around $20 per vote will be spent on political advertising in this year's presidential campaign.

Yet there are reasons for hope. Citizen interest in this year's primaries is high because there is no obvious winner and genuinely different candidates are competing on both sides. The Internet has greatly increased the opportunity for non-establishment, underfunded candidates to develop viable grass-roots campaigns. Voter questions and candidate answers in town meetings are now the standard. In other words, this year's election process so far seems more open and democratic than ever.

Around $20 per vote will be spent on political advertising in this year's presidential campaign. By commercial standards, and given the importance of the purchase decision, that doesn't seem high.

What's needed in politics is not less marketing but better marketing: focusing on current and emerging customer needs, developing product and service solutions, informing interested citizens about them, and making them easily accessible. I remember Leonard Marsh, 1 of the 3 founders of Snapple, explaining the brand's success: "We never thought of ourselves as any better than our customers." Politicians need to view citizens not as occasional voters, donors, and taxpayers but as their customers.

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