Barack Obama has begun a hard hitting advertising campaign portraying John McCain, his Republican rival for the Presidency as being out of touch with ordinary people.

The commercials, which will be run in key states in the run up to the November elections, attack Senator McCain for being disconnected with the economic struggles of the voters and wedded to unpopular policies

In strong contrast to the mainly positive advertisements promoting his vision for the country, the latest campaign is sharper and more aggressive.

One advertisement that is being shown in eight major cities throughout states such as Philadelphia, Michigan and Wisconsin contrasts a statement by Mr McCain claiming "we have had a pretty good, prosperous time with low unemployment," with statements from ordinary people that say quite the opposite. "It is the bleakest of times," says one woman while an Ohio voter says: I'm worried, I'm really worried." As the screen fades to black, a message appears saying 'How can John McCain fix the economy, when he doesn't think it's broken?'"

The advertisements make no mention of the fact that Mr McCain's statement was made during a debate in January, before the economy suffered a downturn.

They are being run on local stations although nationally Mr Obama's advertising campaign remains positive. The offensive is the first example of negative advertising by his campaign that hasn't been in response to an attack on him by Mr McCain.

In recent weeks, the McCain campaign has launched a sustained and not always accurate attack again Mr Obama, claiming, wrongly, that he opposed nuclear energy and comparing his popularity to the celebrity of Paris Hilton and Britney Spears.

In total, the Democratic candidate has released six television commercials and two radio spots against Mr McCain. Two spots that ran over 600 times in a single day last weekend cost the campaign nearly $US400,000.

"If you can go quietly negative, that's what he's done: I think the perception is that he's still running the positive campaign," Evan Tracey, president of TNS MEdia Intelligence, a company which monitors political advertising, told the New York Times. "It's a pretty smart, high-low, good cop/bad cop strategy."

The Republicans have attacked the Obama campaign's new strategy, pointing to his promise to refrain from mud slinging. Tucker Bounds, a McCain spokesman, said: "Barack Obama's been reduced to a sucker-punch strategy, shirking his 'new type of politics' in favour a more negative campaign."

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