NASHVILLE, Tenn. – The presidential candidates turned a town hall debate Tuesday night into a festival of blame, issuing dire warnings about the other’s ability to rein in huge deficits and corral an economy spinning out of control.

“The last president to raise taxes during tough times was Herbert Hoover,” John McCain said, linking rival Barack Obama to the Depression-era president.

Obama fired back, saying, “We are in the worst financial crisis since the Great Depression,” adding that he blamed “failed economic policies of the last eight years” – policies he accused McCain of abetting.

McCain offered the boldest-sounding prescription to the crisis, saying that as president he would immediately order the Treasury secretary to start buying mortgages from people who now owe more than their homes are worth, to let them avoid foreclosure and stabilize home values. The plan, aides said, would cost $300 billion.

“It’s my proposal. It’s not President Bush’s proposal. It’s not Senator Obama’s proposal,” McCain said.

Obama made no effort to pick apart the idea. After the debate, aides pointed out that the bailout package Congress just enacted gives the Treasury the authority McCain would invoke, and they noted that Obama voiced support two weeks ago for direct mortgage purchases.

The senators squabbled repeatedly over the missteps that led to the crisis, each accusing the other of ties to housing finance giants Fannie Mae and Freddie Mac.

Obama tried to turn the page on that, telling one voter in the audience, “You’re not interested in hearing politicians point fingers. You’re interested in how this affects you.” Even so, he went out of his way to link McCain to the huge budget deficits that have accrued under President Bush.

Economic malaise dominated the night. Stock markets are reeling. The credit crisis has spread around the globe. Retirees have lost $2 trillion worth of savings. Voters at Tuesday’s town hall-style debate in Nashville were angry about the $700 billion Wall Street bailout and scared it won’t work.

And they were looking for reassurance, and solutions.

For McCain, the goal was clear and daunting: expose the Democrat as woefully underprepared and reclaim the momentum. He conceded Michigan last week and lags by widening margins in Pennsylvania and other critical states. Allies, including his own running mate, have prodded him to take on Obama as aggressively as possible.

Obama was hardly in a position to coast, despite growing leads in national and state-by-state polls and the contest down to the final four weeks. His task, analysts agreed, was to highlight a superior mastery of economic policy and, if possible, provoke McCain into an intemperate outburst to show himself plausibly presidential for those still skeptical about his short time on the national stage.

Ahead of Tuesday’s debate, they softened each other up with days of caustic personal attacks, the opposite of the civil discourse each promised. Tuesday’s format made that sort of nastiness awkward, though.

Obama has portrayed McCain as “erratic in a crisis” and harped on his role in the infamous Keating Five scandal. McCain has called Obama “dangerous,” and Gov. Sarah Palin accused Obama of “palling around with terrorists” – by most independent accounts, a hyperbolic description of his relationship with William Ayers, the Weather Underground founder turned Chicago community activist.

Sen. Lamar Alexander, R-Tenn., a McCain supporter, felt such attacks would be less effective than tackling the crises weighing so heavily on voters.

“That’s not what most people want to hear. …

“Times are tough,” he said. “Ideology, character and values is an important part of the presidential race, but the pocketbook and terrorism is by far the bigger part. And it’s to McCain’s advantage, it seems to me, to say that in tough times, we need a tough guy for president.”

The bipartisan Commission on Presidential Debates assigned the Gallup Organization to recruit uncommitted voters from the Nashville area. Moderator Tom Brokaw of NBC News chose questions from them and from others submitted via the Internet.

The format made ducking tough or oddball questions a delicate task.

“You have a live voter standing there,” said Diana Carlin, a University of Kansas professor who studies presidential debates. “It’s more difficult to be evasive.”

With economic anxiety at a fever pitch, Carlin said, voters were looking for empathy and answers.

“They don’t expect a silver bullet,” she said. “They realize that a president doesn’t wave a magic wand, (but) don’t stand up there and tell me your plan is XYZ. Tell me why your plan is better and how you’ll get Congress to accept it.”

It turned out that ordinary voters – at least as screened by Gallup and Brokaw – wanted to hear more about issues the candidates have gone over time again: health care, budgets, taxes, the Wall Street meltdown. One notable curveball came at the end, when Brokaw posed a question submitted via the Internet by Peggy from Amherst, N.H., a question he said had a “zenlike quality”: “What don’t you know and how will you learn it?”

Obama retreated to spousal humor, noting that his wife could give a much longer list than he could. He then predicted that as president, “it’s never the challenges you expect” that consume most of your time.

McCain wove in an allusion to his prisoner-of-war days, then argued that dark days require the sort of leadership he alone can provide. “What I don’t know is what the unexpected will be,” he said, but “I know what it’s like to keep one’s hope going in tough times. … We need a steady hand at the tiller.”