That Mitt Romney's coronation as Republican nominee barely moved the needle in his favour was widely interpreted as a worrying sign for his campaign.
It is too early to say with any certainty whether the Democratic Convention in Charlotte, North Carolina, which concluded on Thursday night, has done much for Barack Obama's standing. His team will hope for a narrow lead to carry into the debates so that Romney will be forced to take risks. Statistician Nate Silver's electoral forecast, which aggregates polls and compares them to historical data, gives Obama a 77% chance of winning in November.
Bill Clinton went into last week's convention as one of the most popular politicians in America, viewed favourably by two-thirds of the electorate. He delivered by far the most positively received speech, reviving memories of his own nomination in 1992, which set the benchmark for convention bounce – he was lifted by upwards of 20% in the polls. Some Democrats worry he upstaged Obama.
Most felt that the Democratic event as a whole was more convincing than the Republican convention in Tampa, Florida: more star power, more energy in the hall, fewer speakers with one eye on the next presidential election in 2016, and no off-message moments to rival Clint Eastwood's bizarre conversation with an empty chair.
Washington Post columnist Eugene Robinson wrote: "You can't conclude that just because the Democrats' three-day infomercial was better than what the GOP put on, Obama is going to win. But even if the conventions aren't remotely as important as they once were, they're not meaningless. They do say something, and this year the message for Democrats is decidedly hopeful."
Robinson serves as the liberal counterpoint to a staunchly conservative comment section in the paper. Jennifer Rubin, in the same pages, argued that Obama's speech was short on inspiration and devoid of substance.
She said: "Like an ageing rock star, president Obama, in a downsized venue, with downsized proposals and spewing downsized rhetoric only reminded us how far he has fallen from the heady days of 2008. He leaves the field wide open for Mitt Romney to be the adult in the race, the responsible leader."
Elsewhere, Republican image consultant Peggy Noonan derided Obama's speech as "stale and empty". And Charles Krauthammer pronounced himself "stunned" on Fox News. "This is a man who gave one of the great speeches of our time in 2004, and he gave one of the emptiest speeches I have ever heard on a national stage," he said.
The majority of Americans experience the conventions through this filter, hearing only what they want to hear. Around 20 million people watched each of the main speeches, but in an era when CNN's attempts to report from the centre are consistently outflanked by Fox News on the right and MSNBC on the left, delivering an openly partisan version of events, it requires a conscious effort to listen to the original, un-spun content.
The original purpose of the conventions was to reconcile competing groups within the parties, in order to choose an acceptable candidate with a good chance of winning the election. This ceased to be the case following the 1976 Republican Convention, when Ronald Reagan almost snatched the nomination from Gerald Ford, and the 1980 Democratic Convention, where Ted Kennedy wooed delegates from the sitting president, Jimmy Carter. In both cases, the nominee was damaged and lost the ensuing election.
Since then, the paramount aim of the conventions has been to present a unified front, without any discord or slip-ups – and to take advantage of a few hours of free advertising on prime-time network television. But in this first presidential election since the Supreme Court's Citizens United ruling unleashed a tidal wave of anonymous corporate money in politics, their importance has been diminished still further. In the swing states, the same messages that the conventions sought to convey can be heard all day, every day, on virtually every channel, with even less nuance or moderation.
Research group the Centre for Responsive Politics estimates that the two parties and their Super PAC supporters will spend upwards of $5.8 billion on their campaigns, making this by far the most expensive election ever. The conventions can hardly be considered value for taxpayer money (each party receives $18.2 million from the federal treasury), but the cost of staging them is a drop in a bucket by comparison.
According to veteran White House correspondent Walter Shapiro, the sheer volume of political messages on the airwaves is unprecedented: "Almost all this advertising onslaught will be unleashed during the run-up to the November election. In that final 100-day frenzy, the presidential candidates will become the largest TV advertisers in America - Nothing in political history will have matched the relentless firepower of [these] living-room wars."
Obama alluded to this in his convention speech, saying: "Trivial things become big distractions. Serious issues become sound bites. And the truth gets buried under an avalanche of money and advertising. If you're sick of hearing me approve this message, believe me, so am I."
But his campaign has been every bit as negative as Romney's. And outside groups, with no need to take responsibility for their attacks with that traditional American political disclaimer – "My name's George Washington and I approve this message" – have been more brutal still. The Wesleyan Media Project, which analyses trends in political advertising, found that 70% of commercials in the Republican nomination contest and presidential election so far have been negative in tone, tearing down the opposition rather than promoting a platform.
"It is definitely tilting more negative than elections in the past," said Bill Allison, editorial director of the Sunlight Foundation, which advocates for more accountability and transparency in politics. "The majority are always negative, because that's what works, but we're verging on a point where nobody has anything good to say about any politicians."
The temptation is to conclude that voters are cynical about this advertising and immune to its messages, but to Erica Fowler, the associate professor who runs the Wesleyan Media Project, that would be a mistake. She said: "Campaigns are not going for efficiency, they are going for moderate voters in the centre who have not made up their minds. There are going to be many, many people tuning out the messages, but in a competitive election cycle, you really are going for that last one or two percentage points. So the parties and the interest groups - [are] going to do whatever it takes to get a competitive advantage."
That means spending money where it has the greatest impact, which means in swing states such as Ohio, Florida, Nevada and Colorado. For residents of the most hotly-contested districts, there is no escape from the advertising. "It is highly concentrated this year," said Fowler. "You're seeing far more ads crammed into a smaller airspace than the last presidential cycle."
Allison lives in Virginia, a state Republicans believe they can take back, despite Obama's relatively comfortable 6.3% margin of victory last time. "You can't tune it out entirely," he said. "Maybe you can fast-forward it at home when you tape a show, but if you're at the mall, or waiting to get your car fixed, they have TVs there and you're going to be exposed to the ads no matter what you do."
No community has been bombarded with quite as many commercials as the Ohio town of Mansfield, midway between Cleveland and Columbus, which gets local broadcasts from both cities. Viewers there were subjected to 12,000 political adverts in July alone; an average of 400 per day, or 16 every hour.
This all has to be paid for, of course. George W Bush's spin doctor, Karl Rove, is fond of pointing out that Obama has attended twice as many fundraising events as his old boss did during his first term as president. The convention can be seen as a glorified reception for big-ticket donors, an extended opportunity to flatter them with the promise of influence, introduce them to powerful people and entreat them to get out their chequebooks.
But the convention's hold on the headlines lasted less than a day. On Friday morning, the Department of Labour reported that American employers created 96,000 jobs in August, fewer than expected. The unemployment rate dropped from 8.3% to 8.1% but this was mostly because of people dropping out of the workforce, rather than any surge in hiring.
"There's almost nothing the president's done in the last three-and-a-half, four years, that gives the American people confidence he knows what he's doing when it comes to jobs and the economy," said Romney.
Campaigning in New Hampshire, Obama admitted that the figures were disappointing, but attempted a positive spin. "Today we learned that after losing over 800,000 jobs a month when I took office, business once again added jobs for the 30th month in a row – total 4.6 million jobs," Obama said. "But that's not good enough. We know it's not good enough. We need to create more jobs faster."
The first presidential debate, about domestic policy, is scheduled for October 3. The air wars will continue unabated.