Washington - With the US and global economy in turmoil, it was the trials and tribulations of a budding small business owner, "Joe the plumber," that took centre stage in the final debate between US presidential candidates Barack Obama and John McCain.

Battling for the vote of ordinary middle-class Americans just three weeks before the general election, both candidates apparently decided the economic woes facing the country were embodied in Joe Wurzelbacher, a man who made an appearance at an Obama election rally in Ohio.

Joe, who was first raised in Wednesday night's debate by McCain, had complained at the rally that he could not afford to buy his own plumbing business because of Obama's plan to tax wealthy Americans.

The plumber made numerous appearances throughout the debate as both McCain and Obama promised to lower his taxes, improve his health benefits and prospects of running a small business with the US economy on the verge of a recession.

The debate at Hofstra University in New York state was focused solely on domestic policy, but the exchanges also mirrored the changing dynamic of the last few weeks.

A financial crisis threatening to bring down the US economy has dominated the final stretch of the general election and helped give Obama a commanding advantage.

Obama leads by 7.3 percentage points nationally and in most key battleground states according to an average of all opinion polls compiled by realclearpolitics. com.

With that in mind, it was McCain who came out more aggressively Wednesday and managed the tempo through much of the final debate.

McCain spoke of cutting spending, lowering taxes and prioritizing mortgage-holders struggling to keep their homes. He attacked Obama for wanting to raise taxes during tough economic times.

Obama countered that he would lower taxes further for middle-class workers, and in a regular refrain linked McCain to the economic policies of President George W Bush.

Many media pundits called it McCain's best performance of three debates, though opinion polls suggested Obama had still come out the stronger debater.

But neither performance is likely have a significant effect on the election campaign. Just how badly the US economy fares between now and November 4 will be key.

With an unpopular Republican president at the helm during a serious economic downturn, opposition Democrats have watched the electoral climate swing dramatically in their favour over the last few weeks.

Obama has consistently been favoured over McCain on economic issues.

"The past month has taken an enormous toll on the McCain campaign," Karl Rove, who orchestrated Bush's two electoral victories, wrote in the Wall Street Journal Thursday.

Rove believes McCain must hammer home the argument that Obama will raise taxes during difficult economic times.

Obama promises middle-class tax cuts but has made no apologies for seeking to raise taxes on wealthier Americans.

One thing is clear: "Joe the plumber" is now the most sought after voter in this race. (dpa)