5:52 p.m.: As I have in the past, I’ll be liveblogging for the next 90 minutes or so as Barack Obama and John McCain go head-to-head in their second matchup, this time a town hall debate in Nashville.

Usually such formats are informal, but the stakes are so high for both candidates that it will be interesting to see how each operates in that environment. McCain has been especially hard hitting in his attacks in recent days, and Obama’s campaign has struck back. But it’s not certain how well that kind of sparring will play before an audience of 80 real, presumably undecided voters, perhaps more concerned about their plunging retirement savings than a former Weatherman. See: Ayers, Bill.

There is no stage for this debate, but a horseshoe “theater in the round,” with an almost blindingly red carpet. Tom Brokaw moderates at Belmont University.

6:03: McCain and Obama took the stage, and shooks hands. McCain looked Obama right in the eyes — perhaps as a reaction to criticism that he never looked at his rival in the last debate.

6:04: Economy right off the bat. The question is what will Obama do to help the average Joe. He takes the opportunity to slam Bush and McCain on the economy, as well as corporate CEO salaries. He offers a laundry list — “You need someone working for you, and you need someone who will look out for the middle class.”

“Senator Obama, it is great to be with you at a town hall meeting,” he says, in a slam to Obama’s refusal to debate.

“I think this problem has become so sever that we have got to do something about home values.” Pacing back and forth, he says he will work to help people make payments “and stay in those homes.” He insists it is his proposal.

6:09: Who have in mind for treasury secretary? McCain cites Warren Buffett, “a supporter of Sen. Obama,” and one of his own supporters, Meg Whitman of eBay.

Obama: “Warren would be nice.” Obama repeats past agreements: “Sen. McCain is right we have to stabilize housing prices, but underlying that is loss of jobs and loss of work.”

6:12: The attacking McCain hits Obama on Fannie Mae and Freddie Mac and his “cronies” in Washington. For the record: Obama hit first.

McCain: “There were some of us who stood up against it; there were others who took a hike.”

6:14: Obama hits McCain on deregulating, and Obama cites letters he wrote in 2007 “You are not interested in politicians pointing fingers, you are interested in how this affects you.”

6:17: Is the economy getting better or worse. “I am confident about the American economy,” Obama says.

“I think it depends on what we do,” McCain says, before mentioning again the plan to buy up mortgages.

McCain seems a bit more emphatic tonight, while Obama seems a tad shaky. This reflects the feeling going in that town halls have been a better format for McCain than Obama.

6:20: Obama says that he is “cutting more than he is spending.”

McCain cites his “clear record of bipartisanship.” He slams Obama for not taking on the members of his party. “This is the most liberal big spender in the Congress.”

McCain slams Obama for voting for $3 million for “an overhead projector for a planetarium in Chicago.” (I like that planetarium!)

He’s also really pushing energy independence, perhaps as an overarching issue that his campaign needs.

6:25: A list of priorities — energy, health care, entitlement reform. Once again, McCain is again pushing energy independence, but he says, “We can do them all at once.” McCain seems to be struggling a bit on this one — perhaps showing his age.

“We have to priorities,” Obama says. 1. Energy. 2. Health care. 3. Entitlement reform.

6:28: A good question via email: What sacrifices will you ask the American people?

McCain says will have to “examine every agency.” He cites specifically defense spending, earmarks. “Some of them that are really good projects will have to do as well.”

Obama adds a dose of inspiration to his answer, with plans to double the size of the Peace Corps and to call on all Americans to conserve energy.

6:30: McCain slams Obama for putting health care above energy. It’s biting — perhaps the most effective so far. But this isn’t a stunning debate so far. I haven’t heard much at all off the stump scripts. Moreover, Brokaw has had to adminish them several times for going on too long.

6:34: McCain compares Obama to Herbert Hoover. “My friends, the last president to raise taxes during tough times…” He slams his tax policies, but denies he is in favor of tax cuts for the wealthy. McCain is very emphatic on this — and even smiles a bit as he walks back to his seat. It’s a bad habit that he’s curbed recently, but bad habits die hard.

6:41: “I’ll answer the question.” McCain seems to cut Tom Brokaw off.

6:43: McCain cites his opposition to the Bush administration on climate change, but then points to nuclear power first as a solution. He is so far not as much an attack dog as had been predicted, but is trying to infuse his campaign with grand, optimistic programs. The era of big government isn’t over. It’s in its rebirth.

6:46: Once again, Obama is mentioning where he agrees with McCain. His campaign has probably has made the calculation that it is not a negative, but a positive.

6:48: Brokaw admonishes both on time, again. “I’m just trying to keep up with John,” Obama says. It is vaguely patronizing, like something a grandkid would say to his feeble grandfather.

McCain does do well in the town hall format, but there are two strikes against him this evening. He’s read off notes several times, and the generational factor is more pronounced between the two. McCain has a slight limp, as a result of his war injuries, so I wonder if this will make any difference in terms of perceptions, subtle or otherwise. I hate to bring up the age issue, but as we have learned from past debates, surface stuff seems to matter.

6:53: McCain hits Obama for government-backed and mandated healthcare — something that Obama actually hit Hillary Clinton on during the primaries. This is one of the contradictions of the McCain campaign in recent weeks — he is alternately for big government solutions and against it. It’s a reflection of how much the bailout plan and financial crisis has changed the dynamic.

6:58: Obama has improved considerably in terms of coherence since the start, especially on the health care matter.

7:00: “America is the greatest force for good in the history of the world,” McCain says. This is part of McCain’s stump speech, but it is an effective line. He acknowledges national security mistakes, and cites his record and judgment on sending troops to Beirut (he was against it, which may surprise some) and Kuwait (he was for it). Then he hits Obama’s judgment in not supporting the surge.

7:03: Obama hits back, and connects national security to the economy, something that many on the left have been hoping he would place more emphasize more. “We don’t have the resources or the allies to do the things we should be fundamentally be doing.”

7:05: McCain says the occupant of the White House needs “a cool hand at the tiller.” He again brings up his opposition to troops in Lebanon, despite it being the policy of “my hero” Ronald Reagan. This is essentially McCain trying to limit any inroads Obama has made on the question of national security judgment.

7:11: McCain acknowledges a “serious mistake” in Afghanistan for drawing down troops and letting the Taliban return. He slams Obama for saying he would go into Pakistan after bin Laden without the approval of Pakistan. “Use force, but talk softly, and carry a big stick.”

7:13: “I’m just a hired help here,” Brokaw says as they go overtime.

7:14: Obama challenges McCain’s Rooseveltian quote. “This is the man who sang bomb, bomb Iran, and he threatened to annihilate North Korea,” he says. He has vowed to kill bin Laden.

7:15: McCain says he was joking with a veteran friend “who joked with me about going into Iran.”

7:18: McCain says that Obama is correct on some things in regard to Pakistan.

7:19: McCain’s answer on Russia sounds much more measured than I have heard him before. “It will not be a reginition of the Cold War, but it is challenge.”

Obama, once again: “For the most part I agree with Senator McCain…” But he also says that the U.S. has to offer “moral support” to the former Soviet republics. His message: “We have got to be much more strategic is we are to deal with all of the challenges that we have out there.”

7:24: Is Russia a new evil empire? Obama: “They have done evil things.” McCain: “Maybe.” “The Russians, I think they have got to understand they are facing a very firm and determined United States of America.”

7:26: A strong answer from McCain on Israel. “We can never allow a second Holocaust to take place,” McCain says. Obama’s answer is slightly more measured. But McCain is doing less saber rattling, and more effort at showing how he is discerning in his judgment.

7:30: What don’t you know, and how will you learn it? Obama gives more of climax to the evening than an answer.

McCain: “What I don’t know what all of us don’t know, and that is what is happening, both here at home and abroad.”

“What I don’t know is what the unexpected will be.”

7:34: It’s over. I hate to sound like a broken record, but it is hard to see how this changes the dynamics.

A few thoughts: John McCain was better in town hall formats, more at ease, but not as full of humor as he has been in past town halls, perhaps in keeping with the very uncertain times.

Barack Obama did better than expected in this format.

Neither candidate spent much time overall connecting with voters, but spent a lot of time explaining the Washington bailout.