Could the pollsters’ UK failings hold the secret of next Tuesday?

For political gamblers this election could not be closer and it’s going to come down to how you read the opinion polls – both state and national. Of the five latest, three have moved to Bush and two have moved to Kerry.

Polling round-up showing variance of margin on last poll
Bush 50 Kerry 45 Fox Kerry +2
Bush 47 Kerry 48 DCorps Bush +1
Bush 46 Kerry 47 Zogby tracking Kerry +1
Bush 46 Kerry 46 TIPP tracking Bush +2
Bush 50 Kerry 44 Newsweek Bush +3

The big issue that polling experts are debating is what will happen to those who say they are still undecided – but will vote. How will they split between the incumbent and the challenger?

It’s on the incumbency split that this election will be decided.

One theory that certainly chimes with the years of underpolling of the Tories in the UK is that Kerry supporters might be more likely to tell this to a machine in an automated poll than “to admit to a fellow citizen that they were going to abandon a likeable, steadfast, patriotic wartime leader and vote for a dull, equivocating, aristocratic former anti-war activist.”

There’s hard evidence that this can happen from the 2001 UK General Election where Rasmussen’s interviewer-free polls were the only ones to get the Tory share correct. With a single exception all polls where those surveyed were interviewed underestimated the Tories. But is the US the same?

The “Mystery Pollster” writes this of Survey USA – which does automated polls. I think I see evidence of this in the polls by SurveyUSA in Florida, Ohio, Pennsylvania and Michigan. In each of those states, SUSA has Bush matching the RealClearPolitics average but has Kerry running a few points higher. Their surveys always show a higher undecided than most other surveys, and Jay Leve, SurveyUSA’s director has always speculated it is because their recorded interview better simulates the solitary experience the voting booth. At the same time, I see an opposite pattern in Iowa, Missouri and Colorado – so perhaps I’m just data mining. I want to watch this closely over the weekend.

If this proves to be correct it will completely change the way we look at polling for the coming UK General Election. Meanwhile there’s been a distinct move back to Bush in all the betting markets in what looks like a response to the Osama video.

Betting round up – 0730 GMT Sunday
Bush 55.7 Kerry 44.3 Iowa Political Futures Market
Bush 55 Kerry 45 Tradesports exchange
Bush 1.75 Kerry 2.32 Betfair exchange
Bush 8/13 Kerry 6/4 UK bookmaker best price