PHILADELPHIA/DAVENPORT (Iowa) - DEMOCRAT Barack Obama praised his rival John McCain for toning down the vitriol of the US presidential race on Saturday but pressed an effort to cast him as out of touch on the economy.

Mr McCain faced fresh troubles after an ethics inquiry found that his running mate, Alaska Gov Sarah Palin, abused her authority in a matter involving the firing of a state trooper.

At at raucous rally at a theatre in Davenport, Iowa, the Republican White House nominee made no mention of the Alaska inquiry but described Mrs Palin as someone who would help him shake up government.

'I can't wait to introduce her to Washington DC,' Mr McCain said. 'One thing I heard from Americans at every stop is they're angry - they're angry about the mess in Washington.'

'I'm angry too. When Sarah Palin and I get to the White House we'll turn Washington upside down,' the Arizona senator added.

With just over three weeks left before the Nov 4 election, polls showed a growing lead for Mr Obama, 47, as voters anxious over the turmoil on Wall Street have given the Democratic candidate higher marks for economic leadership.

Mr Obama sought to bolster his perceived advantage on the economy on Saturday as he toured Philadelphia, the biggest city in the battleground state of Pennsylvania.

A street-fair atmosphere prevailed at a series of neighborhood rallies, as Mr Obama spoke on outdoor stages decorated with giant American flags.

The four rallies, aimed at boosting turnout in a strongly Democratic city, were held one after another in various parts of Philadelphia and drew a combined total of about 60,000 people.

'I know these are difficult times. I know a lot of you are worried. But I also know that now is not the time for fear or panic,' Mr Obama said, adding that Mr McCain 'doesn't really seem to get what's going on.'

Milder tone
But before launching into his attack, Mr Obama thanked Mr McCain for having tried to 'tone down the rhetoric' of his campaign.

The Illinois senator was responding to an incident on Friday in which Arizona Sen McCain urged one of his backers to take a milder tone.

When one woman at an event said she did not trust Mr Obama and raised a false assertion that he was an 'Arab', Mr McCain replied that Obama was a 'decent person and a person that you do not have to be scared (of) as president of the United States.'

But Mr McCain, 72, said he thought he would be a better president than Obama.

Mr McCain's comment amounted to a defence of Mr Obama's character and seemed at odds with a Republican strategy of trying to raise voter questions about Mr Obama by highlighting issues like his past association with Chicago college professor who was once a 1970s radical.

On the issue of character, Mr Obama returned the compliment, calling McCain honourable and invoking his service in Vietnam, where he was tortured as a prisoner of war.

'I'm one who believes that we can all respect each other, even when we disagree, especially when it comes to a veteran of our wars because those folks lay down their lives to protect us,' Mr Obama said.

In an indication of the anger running high on both sides, the crowds at Mr Obama's Philadelphia rallies booed loudly at the mere mention of Mr McCain's name. In Davenport, Mr McCain's supporters jeered when Mr Obama's name was brought up.

Mr McCain laced his speech with criticism of his rival on everything from taxation to health care, but refrained from any serious character attack.

The Palin ethics scandal centred on whether the dismissal of the state's public safety commissioner, Walt Monegan, was linked to the governor's personal feud with a state trooper involved in a contentious divorce with Mrs Palin's sister.

The inquiry found that while it was within the governor's authority to dismiss Mr Monegan, she violated the public trust by pressuring those who worked for her.

The McCain campaign dismissed the report, saying it was a 'partisan-led inquiry run by Obama supporters.'

Mrs Palin 'acted within her proper and lawful authority in the reassignment of Walt Monegan,' a campaign statement said.

Neither Mr Obama nor his campaign have commented on the Palin ethics matter.

A Newsweek poll published on Friday showed Mr Obama ahead of Mr McCain by 52 per cent to 41 per cent. A month ago, that poll had the two candidates tied at 46 per cent. Other polls in the most contested states have also shown a swing towards Mr Obama. -- REUTERS