Click through for a running commentary on tonight's showdown. And please weigh in with your own opinions!

During tonight's debate, Caleb Howe, Tom Fitzsimmons, and I will be doing a running commentary. Click Here to listen live at 9 pm.

While we comment on the goings-on, Christina and Diana will be fact-checking on the fly in the comments section here. We'll periodically move that information up here to the body of the story.

The best way to enjoy this is to keep this window open next to the radio show window, and refresh it periodically. This is our first attempt at something like this, so bear with us, and hopefully we can all enjoy the debate together.

Tonight's debate between Barack Obama and John McCain at Belmont University in Nashville, TN will be in a highly structured town hall-type style with the pre-screened questions coming completely from undecided, but likely, voters rather than a moderator.

There will be a moderator, NBC's Tom Brokaw, who has the final authority on the questions selected. from a field of 100-150 pre-submitted questions from the audience and a few more submitted from the internet. The Gallup Organization has the responsibility to make sure that the questions come from a representational mix of the population.

There will be chairs and the debaters will be allowed to take notes, but not bring any. A new twist with this town hall debate is the inclusion of what some call the "Lazio Rule" (named after NY's Rick Lazio who got in HRC's face during a senatorial campaign debate). McCain and Obama will not be allowed to stray from their designated areas lest they violate the other's space.

The questioners will ask their questions and then the mike goes off. No follow-ups allowed by the questioner or the moderator - but Politico's Ben Smith says, "...Brokaw wasn't a party to the deal, I'm told, and hasn't agreed to it, so the campaigns are expecting follow-up questions, a senior campaign official said."

This style is said to be John McCain's strong suit. For his sake, he'd better hope so. He needs to stop the bleeding in the polls. With 28 days to go and only one more debate after this one, he doesn't have too many more opportunities to sell himself to the American people - many of whom are only now waking up to the fact that there's an election happening soon.

The debate will air on most news channels at 9:00 eastern time and will run 90 minutes. Stop back for our live coverage.

The drip, drip, drip of information about the exact nature of the relationship between Sen. Barack Obama and former domestic terrorist and 60's radical William Ayers continued today as the Obama campaign admitted for the first time that Sen. Obama did know of Ayers' history as the head of the notorious Weather Underground. That line directly contradicts what the campaign said yesterday, that Sen. Obama did not know who Ayers was when he worked closely with him on the boards of two separate organizations in the late 1990's and early 2000's. Worse for the campaign, the admission essentially confirms Gov. Sarah Palin's claim from this past weekend that Obama, "pals around with terrorists."

Obama campaign chief strategist David Axelrod told the Chicago Tribune that Obama learned of Ayers' role as leader of the Weather Underground, which declared war on the United States and carried out a string of bombings at targets including the U.S. Capitol, the Pentagon, and New York City Police Headquarters, "sometime after," a 1995 fundraiser that Ayers held for Obama at his Chicago home.

"It was sometime after their first meetings, you know, he became aware of that. I don't know the exact moment.

I mean the fact is, like a lot of people who, you know, didn't live through that era, particularly who didn't live through that era in Chicago, it just wasn't, I mean, when [Obama] came to Chicago, Ayers was advising Mayor Daley on school reform issues and that was his profile was that he was an expert on education issues.

My understanding was that he, when he went there [to Ayers' home], he did not know, so I would say after. No one is suggesting that he never knew. I mean that's not, we weren't offering that."

But that is exactly what the Obama campaign was offering, just yesterday.

There are still more details of the Obama-Ayers relationship that the Obama campaign has not owned up to. The campaign will not confirm the exact nature of the working relationship between the two men at the Chicago Annenberg Challenge, an education funding initiative started by Ayers and headed by Obama as Ayers' his hand-picked chairman. The projects that the Annenberg Challenge funded were administered by a separate group known as The Collaborative, which had Ayers as its chairman. Obama would have to have been familiar with the Collaborative's projects in order to recommend them to the Annenberg Challenge board for funding. That belies a close working relationship. The two also served together on the board of the Woods Fund between 1999 and 2002. During that time, Ayers' now infamous September 11th, 2001, op-ed was published by the New York Times and he was photographed standing on an American flag for an article in Chicago Magazine.

Axelrod's admission that Obama learned of Ayers' terrorist activities "sometime after" the 1995 fund raiser makes it very likely that Obama knew Ayers was an unrepentant domestic terrorist when he sat with him on the boards of the Annenberg Challenge and the Woods Fund and chose to associate himself with Ayers anyway. The Obama campaign calls the furor over Ayers a smear and a "distraction." But so far, everything that the McCain campaign has claimed about Obama and Ayers has been confirmed by the Obama campaign itself. That hardly makes it a smear. It will be up to the voters to decide if it is a distraction.

The NRA has a new ad out attacking Barack Obama on gun control. The ad features a latino sheriff warning against the evil mexican criminals, complete with mugshots, pouring across our border. From Politico:

It's unclear how widely this spot will air, but it's supposed to go up on TV and radio today. The NRA claims that it will spend "8 figures" on broadcast advertising this cycle.

The ad also features some fast talking about Obama's record on gun issues. Here's the real deal.

The ad also refers to an Illinois state law, claiming Obama voted to allow the prosecution of people who use firearms for self-defense. The law in question, SB 2165, refers only to people using illegal firearms, and prosecutions of the violations of firearms ordinances.

It looks like the politics of fear are in full swing now, with an extra helping of racial demonization to go along with it.

Caleb Howe, Christina Cedeno, Tom Fitzsimmons, and I will be doing live debate commentary tonight on a special episode of Unusable Signal. Click Here to listen live at 9pm, or to hear the archive afterwards.

Charging John McCain with negative attacks designed to change topics, Barack Obama has a new :30 spot titled "The Subject." Pot meet kettle.

Following up on my earlier posts (here and here) on John McCain's new battleground state strategy, the three prizes that he thinks he must have for victory just keep getting more distant.

RCP now has the following numbers for McCain's firewall of Wisconsin, Minnesota, and Pennsylvania:

McCain trails in Wisconsin by 6.7%. Last week, the average was 5%.

He's behind by 10.5% in Minnesota. Last week it was 5%.

And Obama has opened up an 11% point lead in Pennsylvania. Last week it was 7.9%

In each of these three contests, the trend is ominous for Team McCain.

More bad news for McCain: In 2008 Democratic registration is up 13% in Michigan, but down 1% for Republicans.

Tonight's debate is a crucial one for both candidates, especially for John McCain. Although Obama has pitfalls to avoid, McCain stands to suffer a knockout blow if he performs poorly. With Obama's lead growing steadily, McCain could find himself on the wrong end of a high double-digit deficit by week's end, frenetically dodging the insertion of the proverbial fork.

Prior to Saturday, this had already been a nasty campaign, and most observers lay the fetid, slimy wreath at McCain's feet. With Sarah Palin's reintroduction of discredited attacks on Obama's character, the issue of Team McCain's mudslinging will be the 800 pound Pit Bull/Barracuda/Lipstick-adorned Wild Boar in the room. Will Obama wrestle this beast?

Conventional wisdom (and actual wisdom), says that McCain should tread lightly, and try to engage his opponent more to erase the distaste many felt at his refusal to even look at Obama in the first one.

On the other hand, I think it is quite possible that McCain's cold-shoulder of Obama was a deliberate strategy, and not the soaking through of McCain's crankiness. The campaign's current narrative is that Obama isn't "one of us." To those convinced of this, McCain is not making himself look bad, he is shunning an anti-American villain.

Going easy on the slime tonight and winning a thrust-parry-thrust on policy might halt McCain's slide, but it's not going to gain him much. McCain may feel he can make those gains by raising Ayers and Wright at the debate.

On the flip side, holding off doesn't lose him anything, and he can continue the attacks right after the debate.

Obama faces a different choice. Whether McCain brings it up or not, people might be expecting Obama to fight back. As Mo Rocca astutely observed, sometimes it's OK to get mad, and people connect with that. As he also noted, this might play differently for a black candidate.

What would an Obama counter-attack look like? He could fire at McCain about the Keating Five, Palin's witch-hunting pastor, or her ties to a secessionist political party. He could even bring up the rape kits.

I don't think he will go this route. Rather than escalate the fight, I think Obama wants to end it and get back to talking about the economy. He would do well to challenge McCain to have some sense of shame. To attack the character of a fellow US senator, in such a cowardly and dishonest way, after promising not to do so, when the American people are struggling to put food on the table, gas in their cars, and roofs over their heads is not worthy of the office which we seek. Something like that.

Whatever he says, I want the exchange to end like this:

Obama: ...how dare you, sir? (long pause)

McCain: Well, my f...

Obama: How DARE you?

Since writing this story, a senior campaign adviser to Barack Obama tells The Political Machine to "be sure that he will be prepared to hit," and that, "We made a clear decision to hit back and hit hard. It means that not only will we do our best to get our candidate to win, but it also means that by not being Swiftboated, we are telling the American people that we will change politics by rejecting the old school of Rove and Atwater. The American people deserve better.

So, it sounds like Barack Obama is ready to bring the heat tonight. This should be very interesting, indeed.

Caleb Howe, Christina Cedeno, Tom Fitzsimmons, and I will be doing live debate commentary tonight on a special episode of Unusable Signal. Click Here to listen live at 9pm, or to hear the archive afterwards.

Via TaxProf Blog:

Jack Bogdanski (Lewis & Clark) & Bryan Camp (Texas Tech) have independently reviewed the tax issues raised by the release of Gov. Palin's 2006 and 2007 tax returns and financial disclosure form, as well as the remarkable opinion letter issued from Washington D.C. tax lawyer Roger M. Olsen. Jack and Bryan conclude that there are serious errors in Gov. Palin's returns as filed and that she and her husband owe tens of thousands of dollars in additional taxes.

Ouch. The per diem expenses for familial travel seem to be one small problem.

Jake Tapper of ABC News and Dana Milbank of The Washington Post are reporting that the tone being set by McCain's pit bull, Sarah Palin, has crowds turning ugly at campaign events. From WaPo:

Palin's routine attacks on the media have begun to spill into ugliness. In Clearwater, arriving reporters were greeted with shouts and taunts by the crowd of about 3,000. Palin then went on to blame Katie Couric's questions for her "less-than-successful interview with kinda mainstream media." At that, Palin supporters turned on reporters in the press area, waving thunder sticks and shouting abuse. Others hurled obscenities at a camera crew. One Palin supporter shouted a racial epithet at an African American sound man for a network and told him, "Sit down, boy."

And, from Tapper:

This does not appear an isolated incident. Yesterday at a McCain rally, after McCain asked "Who is the real Barack Obama?" a member of the audience yelled "Terrorist!" And so on.

And, lest you think that these are reporters with active imaginations, ask yourself why the press is not allowed to mingle with the crowd at campaign events?

When reporters tried to leave the designated press area and head toward the bleachers where the crowd was seated, an escort would dart out of nowhere and confront him or her and say, "Can I help you?'' and turn the person around.

When one reporter asked an escort, who would not give her name, why the press wasn't allowed to mingle, she said that in the past, negative things had been written.

With Palin employing "Barack the Boogieman" rhetoric, and a speaker at her rally invoking the "Hussein" card, it's not hard to see why the McCain campaign wants the press to stay in their cage, but these things have a way of getting out of control. When these tensions flared during the primaries, the candidates wisely declared a truce, but there doesn't appear to be an olive branch in the offing this time.

Caleb Howe, Christina Cedeno, Tom Fitzsimmons, and I will be doing live debate commentary tonight on a special episode of Unusable Signal. Click Here to listen live at 9pm, or to hear the archive afterwards.