04.12 | Summing up – For my money McCain had a strong night but, without a gamechanger, it doesn’t look like it will be enough. Given that the difference in tone and body-language seems to have made the difference in the first two debates, it’s not a surprise that Obama has picked up the ‘win’ again tonight. Short of a last-minute national security emergency, it’s hard to see what McCain could do to win this election after tonight.

In the meantime, I’ll be continuing to blog the developments and changing strategies of the last 20 days of this race. On election night itself I’ll also have a liveblog of-sorts via Twitter.

03.55 | Joe the plumber – Apparently the AP has reached him, and…drum roll please…. he won’t say which way he’s voting. CBS instant poll of 500 voters is in: 54-22 in favour of Obama in terms of who won. Twice as many uncommitted voters now say they’re in favour of the Democratic nominee.

03.42 | Insta-verdict – GOP pollster Frank Luntz’s sample grew has gone in favour of Obama but which way will ‘Joe the plumber’ have gone?

03.34 | The aftermath – The pundits are picking up on ‘Joe the plumber’ – Mr. Joe Wurzelbacher of Ohio. Oh, and apparently Palin’s son has Down’s Syndrome, not autism. Bit of a mistake for McCain there then seeing as he mentioned autism repeatedly.

03.28 | Closing statements – McCain’s delivered a similar final argument to his one in the previous debate. He talks about his history of reform, he calls himself “a careful steward of your tax dollars” and asks for an opportunity to “serve again. I’d be honoured and humbled,” he says.

Obama talks about the failed policies of the last eight years, and says the biggest risk would be to continue in the same direction and expect a different response. He runs over the key planks of his platform – middle-class tax cuts, healthcare reform etc. – and says he will work “tirelessly on your behalf and on the behalf of the future of your children.”

The candidates shake hands and it’s over. Good job by the moderator this evening.

03.17 | Education – Obama’s playing heir to the JFK legacy, talking about increasing the Peace Corps and offering college funds in exchange for volunteer or military service. Both talk about removing bad teachers and argue the school vouchers issue. Nothing new here.

03.08 | Roe v. Wade and Supreme Court nominations – Culture wars, could either candidate nominate a Supreme Court justice who has a different view on Roe v. Wade? McCain rejects the idea of a “litmus test” and says he will find those with “strict adherence to the constitution.” He walks a very tight line on whether he would nominate someone in favour of abortion.

Obama agrees that it’s important not to apply a strict test and talks about his views on recent decisions and on abortion generally. McCain has 18 minutes left for a gamechanger.

02.57 | Healthcare – Both just recite chunks of the stump speech. McCain then brings up ‘Joe the plumber’ again and says he will be fined for not sorting out insurance, and asks Obama (as he did in the second debate) again for the figure of the fine. Obama says the fine is zero because there is an exemption for small businesses. McCain looks genuinely shocked.

02.47 | Energy and climate change – Schieffer wants a number for how much American dependence on foreign oil can be decreased. Both simply talk about decreasing reliance on the Middle East and turn the question into a free trade debate. McCain says Obama has never been south of the border and seems somewhat surprised when the Democratic nominee is able to talk about the situation in Columbia and Peru. Whoever’s been prepping Obama has done a good job.

02.41 | Running mates – Why would the country be better off with your running mate as President than your opponent’s? Obama doesn’t even bother attacking Palin, he merely points out Biden’s impressive foreign policy credentials and working class roots.

McCain says the American people have “got to know Palin.” He talks through her ‘reformer’ credentials and calls her a “breath of fresh air”. Obama says Palin has “excited the base in the Republican party” and hits back on McCain’s earlier spending freeze, saying that something like autism needs more funding.

McCain says he’s had a lot of foreign policy disagreements with Biden but turns to calling Obama

02.37 | Ayres – McCain: “I don’t care about an old, washed-up terrorist.” McCain says the voters need to know the full extent of Obama’s relationship with Ayres and with ACORN (the organisation accused of voter registration fraud).

Obama says that Ayres is now an education professor in Chicago who committed “despicable acts” when Obama was 8, which the Senator says he condemned. However, he notes that he merely sat on a board with Ayres ten years ago and he’s had no role in his campaign. Obama also says ACORN is nothing to do with his campaign. These are pretty strong denials because they are pretty dubious connections. In rejecting the validity of an attack on Obama’s links with Rev Wright, this is all McCain has been left with.

Obama says that the fact McCain has made Ayres central to his campaign “says more about you than it does about me.” Chalk up a big win for the Illinois senator here.

02.26 | Going negative – “Both of you have pledged to take the high road,” what happened? McCain blames Obama, he says the tone would have been better if the Obama campaign had accepted his plan for ten town-hall debates. McCain asks Obama to refute Rep. John Lewis’s comment.

Obama points out that a recent study shows McCain’s ads are currently 100% negative. He appeals for debate on the issues, and says the American people deserve that.

McCain goes back to Lewis’s comment. Obama says “he inappropriately drew a comparison” with what happened during the Civil Rights Movement, and his campaign put out a statement to that effect.

I can’t see why McCain has brought this up, since it only serves as a chance for Obama to mention some of the comments that have been made at recent McCain rallies: “kill him”, “terrorist” and “Arab” are amonst the highlights. McCain stands by those who come to his rallies and hands Obama the floor to talk about issue disagreements. If McCain won the last segment, and I certainly think he did, Obama won this one.

02.14 | The deficit – Earlier this month, the US national debt clock ran out of digits. Schieffer asks if some of the plans of the two candidates will have to be cut. This is something that they’ve both been asked about in the two previous debates and they dodged the issue. Schieffer asks for specific program cuts.

Obama says his policies will save money, but won’t detail specific campaign proposals which will have to be cut back. McCain would use a hatchet to freeze federal spending, and would then “bring out a scalpel.” He goes on to give a number of specifics including ethanol subsidies.

McCain thinks he can balance the budget in four years. He turns to Obama: “I am not President Bush. If you want to run against President Bush you should have run four years ago.” McCain is hitting hard on Obama’s voting record on budgets, telling the American people that he offers change by cutting down spending. He’s delivering a strong answer here and appealing to those directly hurt by the economy.

02.04 | Economy recovery plan – Why is yours better? McCain opens with a shout out for Nancy Reagan who slipped over and broke a hip earlier today. Keen to avoid any suggestion of not showing enough respect to Obama, McCain turns to him and said he’s pleased to be debating with him this evening.

Both candidates are striking a serious, almost sorrowful tone so far. They’ve both given a summary of their plans – nothing new so far.

McCain is appealing directly to the blue collar workers who voted for Clinton in the primaries, and who have been the reason for Obama’s recent polling surge. In this case he’s talking about ‘Joe’, a plumber from Ohio. Obama again hits McCain’s corporate tax cut.

We’re still on Joe the plumber, the candidates are talking about “spreading the wealth around.” McCain calls Obama’s plan “class warfare.” Is ‘Joe the plumber’ the new ‘my friends’?

02.00 | We’re on – Bob Schieffer has completed his introduction and the candidates are out. They’re both sitting around a desk. It’s odd.

00.45 | Intro – With just 20 days to go until election night, the final debate between John McCain and Barack Obama will likely determine the next President of the United States (short of a last-minute October surprise). It’s no exaggeration to say that the Republican nominee needs a huge victory tonight. He’s trailing significantly in the polls – by as much as 14 points in one national poll released yesterday – and early voting in many states is allowing Obama to begin banking this lead.

McCain’s already tried a number of tactics to reclaim the lead. He suspended his campaing to try and claim authority on the economy issue, and has been running entirely negative ads for the last few weeks. The latter has suceeded only in lowering his own favourables, and boosting his opponents.

Obama has been creditedwith victories in the last two debates in focus group polls while McCain has come in for criticism for not showing enough respect towards Obama. Tonight, the McCain campaign has promised to raise the Bill Ayres issue and expect him to hit Obama hard on his tax plans. Obama, on the other hand, will be happy to play defence all night. He’s survived the debates thus far by keeping his head down and hitting back only when challenged. It’s a route he can take precisely because he is the front runner.

Tonight’s debate will be moderated by Bob Schieffer of CBS, and will be taking place at Hofstra University in Long Island, New York. Join me from 2am when the liveblogging fun begins for the final time. On election night itself (Nov 4) I’ll be liveblogging in limited form via Twitter.