INDIANAPOLIS, Indiana (AFP) - Barack Obama promised Americans "better days ahead" despite another day of carnage on Wall Street and global markets, rising job losses, and dark clouds of economic doom.

The Democratic nominee struck an inspirational note on the day after his latest debate clash with John McCain, but intensified his relentless drive to saddle his Republican foe with President George W. Bush's unpopular legacy.

Obama's call for national steadfastness in the hours of crisis came as he stretched his lead to 11 points in the latest daily Gallup tracking poll over McCain -- less than four weeks before the November 4 election.

"I'm here today to tell you that there are better days ahead," Obama told a 20,000 strong ethnically diverse crowd in Indiana, a once solid Republican state which is now a battleground.

"I know that many of you are anxious about the future. But this isn't a time for fear or panic. This is a time for resolve and leadership," Obama said, vowing the United States would steer its way out of the crisis.

As global stock markets reeled from heavy losses, Obama warned America could not afford another four years of Republican economic strategy.

"I can take four more weeks of John McCain's attacks, but the American people can't take four more years of John McCain's George Bush policies," Obama told a large crowd at the muddy Indiana State Fairgrounds.

"We've seen enough of where that leaves us and we are not going back."

The McCain campaign has in recent days slammed Obama over his past association with William Ayers, a 1960s radical, questioned his patriotism and whether he shares basic heartland values.

In an interview with ABC News, the Democratic nominee accused McCain of trying to score "cheap political points" and reiterated that Ayers committed "despicable acts" 40 years ago when Obama was eight, and that he had merely served on a school reform board with him.

Despite warning that the United States faced a moment of "great uncertainty" Obama vowed to lead the country out of its economic convulsion if he is elected president.

"It will take new leadership in Washington. It will take a real change in the policies and politics of the last eight years," Obama said.

His tone appeared to be an attempt to frame an upbeat message to contrast to McCain, whom the Obama campaign is portraying as erratic and cranky after the latest debate clash.

The McCain campaign shot back questioning Obama's ability to lead and painting him as a "the most liberal" US senator who favors "reckless new spending that will bankrupt our country."

"Barack Obama's proposals for lavish new spending during a financial crisis coupled with job-killing tax increases on small business demand no sacrifice - they simply prove he is not ready to lead," said McCain campaign spokesman Tucker Bounds.

The Democratic nominee's Indiana trip was a bid to stretch McCain's campaign, which polls show is struggling to cling onto states won by Bush in the 2004 election.

Latest surveys give McCain an edge of a few points in a surprisingly tight race in the midwestern state, which has not voted Democrat in a presidential election since 1964.

Obama's vice presidential running mate Joe Biden meanwhile campaigned in another once-staunch Republican state which appears to be wavering as the economic crisis bites.

The Delaware senator said Obama had now got two debate wins and he claimed one over his opposite number, Republican vice presidential pick Sarah Palin.

"If this was a best of five series, it would be over, it would be done," Biden said.

McCain meanwhile held rallies in Pennsylvania and Ohio with Palin, as the dust settled after the presidential debate in Nashville, Tennessee Tuesday.

Several snap post-debate polls said Obama won the clash, following his perceived victory in the first debate showdown two weeks ago.

The latest Gallup Daily tracking poll on Wednesday had Obama stretching his lead nationally over McCain to 11 points.

His 52 percent to 41 percent edge represented his highest point of the campaign and the biggest gap so far between the candidates in the general election.

A Rasmussen daily tracking poll however had the race much closer, but Obama still ahead, giving the Illinois senator a 51-45 percent lead.

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