Barack Obama and John McCain traded shots in a heated debate over the U.S. economy Tuesday night, with Obama calling the credit crisis the "final verdict" on failed Republican policies.

The town hall-style debate was held in Nashville, Tenn., and offered McCain one of the last chances he'll have of halting Obama's recent surge in the race.

"I believe this is the final verdict on the failed economic policies of the last eight years, strongly promoted by President (George) Bush and supported by Sen. McCain," Obama said.

"(Those policies) essentially said that we should strip away regulations and consumer protections and let the market run wild, and prosperity would rain down on all of us. It hasn't worked out that way."

Obama also said that before the credit crisis, McCain had bragged he was a deregulator.

However, the junior senator from Illinois quickly returned his focus to the members of the audience, listening from their seats just a few feet away, and said, "You're not interested in politicians pointing fingers. You're interested in the impact on you."

He then said he would work with Americans to keep their homes, but there needs to be leadership from Washington to set out new guidelines for the financial system.

"This is not the end of the process, this is the beginning of the process," Obama said.

McCain said the U.S. should fix its economy by stopping its reliance on oil from the Middle East.

"I have a plan to fix this problem, and it's got to do with energy independence," he said. "We've got to stop sending $700 billion a year to countries that don't like us very much. And we've got to keep taxes low and stop the spending spree in Washington."

The two leaders had highly different styles during the debate. McCain frequently paced around the hall, walking up to audience members and looking them straight in the eye as he answered their questions.

Obama seemed more relaxed, but appeared exasperated during the more spirited exchanges between the two candidates.

At the start, McCain sarcastically welcomed Obama by saying, "It's good to be with you at a town hall meeting."

McCain had asked Obama to appear with him in a series of town hall debates this past summer, but Obama declined.

At another point, Obama described McCain as an unsteady leader who once "sang bomb, bomb, bomb Iran" to the tune of a Beach Boys song. Obama had brought up the same remark in the first debate.

Tax policy

Much of the back-and-forth between McCain and Obama focused on tax policy.

On a question that asked whether either candidate could be trusted with taxpayers' money, McCain attacked his Democratic rival, saying that when it came to spending, he saw Obama vote "for every pork-barrel project that came across his desk."

McCain told the audience that "nailing down Senator Obama's tax proposals is like nailing Jell-o to the wall."

"I am not in favour of tax cuts for the wealthy," McCain said. "Let's create jobs and let's get our economy going again and let's not raise taxes on anyone."

Obama, initially denied a rebuttal by moderator Tom Brokaw, continued his response to McCain's tax increase claims within a question on health care and social security. He accused the Republican Party of giving a $300-billion tax cut to large corporations and Wall Street executives.

On the issue of energy, Obama said the two candidates agreed on one thing: Washington hasn't done anything about the energy sector in 30 years.

"However, Sen. McCain voted 23 times against alternative fuels," Obama said. "It's easy to talk about this stuff during a campaign."

The event was hosted by Belmont University. Audience members and voters participating through the Internet posed questions for the two candidates.

The final debate is set for Oct. 15 at Hofstra University on Long Island.