By Kevin Anderson
BBC News Online in Washington
Television advertising is such an integral part of modern political campaigning in the US that it is easy to forget candidates had to be sold on the idea in the early days of TV.
Disney designed Dwight Eisenhower's ground-breaking ad
They viewed such advertising as undignified.
When Dwight Eisenhower opened a new era in American politics in 1952 by launching the first television advertising campaign in a presidential race, his Democratic challenger scorned the move.
"I think the American people will be shocked by such contempt for their intelligence. This isn't Ivory Soap versus Palmolive," Adlai Stevenson famously said.
But television ads are now the centrepiece of any presidential campaign, with candidates spending from 50% to 75% of their money on them - and the total spent on them quadrupling every four years.
Television ads are now the centrepiece of any presidential campaign
Political advertisers, including the George W Bush and John Kerry campaigns, will spend an estimated $1.3bn on television advertising this year.
And the airwaves in 17 key battleground states are already saturated with Kerry and Bush campaign ads in the lead-up to the November election.
The early advertising campaigns were relatively simple.
Adlai Stevenson based his TV campaign on 18 half-hour speeches, relying on the speaking skills that swept him to his party's nomination.
But the future of the political ad campaign was already clear.
A Madison Avenue pitchman sold the future President Eisenhower on the idea of running ads before the popular sitcom "I Love Lucy", and Disney Studios produced his "I Like Ike" campaign.
As marketing techniques have become more sophisticated so have the presidential ad campaigns.
Bill Clinton rode his "Bridge to the 21st Century" theme to victory
Images and phrases used in the ads are tested with focus groups.
"Politicians find out what [voters] want and feed it back to them," said Bruce Newman, who advised the Clinton campaign ahead of the 1996 presidential election.
"By early 1994, Clinton was damaged goods," he said. Scandals and the Republican capture of the House of Representatives left him vulnerable as he began his re-election attempt.
Research found that Americans had lost faith in the American dream but wanted a better future for their children, Mr Newman said.
Mr Newman developed the "Bridge to the 21st Century" theme to give voters "an emotional anchor that was bigger than Clinton as a person".
It became central to Mr Clinton's re-election campaign.
The key role of campaign ads is to define both the candidate and the challenger.
Mr Newman said that the most effective ad in history was a 1988 commercial run by George Bush against Michael Dukakis.
The ad accused Mr Dukakis of supporting weekend leave from prison for violent criminals, including Willie Horton.
"Horton fled, kidnapped a young couple, stabbing the man and repeatedly raping his girlfriend. Weekend prison passes. Dukakis on crime," the ad said.
The famous Daisy ad played on Cold War fears of a nuclear exchange
Focus groups had found that voters would turn away from Mr Dukakis if they thought he was soft on crime, Mr Newman said.
"The Willie Horton commercial destroyed Michael Dukakis. That is one ad that turned an election around."
Another famous ad ran only once. The Lyndon Johnson commercial is known simply as the Daisy ad.
It showed a small girl counting as she picked the petals off a flower. When she reached nine, an ominous adult voice counted down to 10 and the scene dissolved into a nuclear explosion.
The ad never mentioned Mr Johnson's opponent, Arizona conservative Barry Goldwater, but it played on public fears that Mr Goldwater would start a nuclear war if elected.
The ad was withdrawn in the face of protests - but it was shown several times on news programmes and featured on the cover of Time magazine.
Rallying the base
Mr Kerry and Mr Bush have been working hard in their ads to define each other.
Republican strategist George Strimple says it is important for George Bush to underline his role as a strong leader.
John Kerry has highlighted his military service in Vietnam
He should reinforce Americans' fear of terrorism and show that he is better able to fight it than John Kerry is.
Mr Kerry highlights his decorated military service in Vietnam in his ads.
And he portrays President Bush as someone who does not tell the truth, who is not up front with facts and who had ulterior motives for attacking Iraq, Mr Newman said.
The internet ad war
With the rise of the internet, ads have moved onto a new battlefield.
Groups such as the conservative Club for Growth and the liberal MoveOn.org are increasingly turning to the internet to broadcast ads that would have aired on TV in the past.
They aim to reach the 65% to 70% of Americans who go online every day, said John Tedesco, a communications professor at Virginia Tech University.
The campaigns also use the internet to circumvent campaign finance reforms that did not anticipate the use of the medium for video ads.
And groups such as MoveOn.org and the Club for Growth are producing some of the most hard-hitting, negative ads of the campaign, Mr Tedesco said.
Negative ads work, which is why campaigns use them, he said, but they also reinforce Americans' cynical view of politics.
And he anticipates this election will continue the negative trend: "If Americans thought they were sick of political advertising in 2000, look out."