The Labour leadership contest has more than six weeks to run. But the view of most is that it's over already. Betfair punters give Owen Smith just a 12 per cent chance of beating Jeremy Corbyn. Most pundits take a similar view.

In my column this week, I write that Corbyn is almost certain to win. He has garnered 187 constituency party nominations (a reliable indicator in 2015) to Smith's 27. But the latter's team argue that they have cause for hope. Private polling, a source told me, shows Corbyn below 50 per cent for the first time (having lost six points in the last few weeks) with a significant number undecided. Such reports should always be treated with caution. Andy Burnham's team claimed private polling showed him four points behind Corbyn last August (compared to YouGov's 32). Corbyn finished 41 points ahead.

But Smith's supporters have also been buoyed by new data from Saving Labour. The anti-Corbyn group says it has recruited 70,000 registered supporters (out of an estimated 140,000) and 50,000 trade unionists (out of an estimated 70,000). Their assumption is that almost all will vote for Smith, putting him level with Corbyn among the former group and ahead among the latter. They also argue that CLP nominations overstate Corbyn's lead among members (the group he performed worst among last time - winning 50 per cent). On PoliticalBetting, the usually reliable Don Brind argues that the race is "too close to call". But Corbyn allies remain confident of victory, with some predicting that he could win by a larger margin than in 2015 (60-40). Neither side believes the expected addition of 130,000 new members will make a significant difference (a court judgement is due at 3pm tomorrow), a large number having already signed up as registered supporters.

The best historical predictor of Labour leadership elections has been YouGov polling (which showed Ed Miliband ahead in 2010 and Corbyn ahead in 2015). Corbyn led Smith by 22 points in the last survey, conducted in mid-July, but this was before the latter's adoption as the challenger. The poll showed that 69 per cent of members either knew "not much" or "nothing" about Smith, showing his potential for improvement. Only with the release of a new survey (expected early next week) will we know for certain whether the "Smith surge" is as mythical as the "Yvette surge" of 2015.