The mayoral race has entered its final lap with the two leading contenders straining madly for the winning tape. The polls still fall into two groups: YouGov's, which continue to show Boris Johnson in the lead, and all the others which show him and Ken Livingstone neck-and-neck. Perhaps the most significant development is that the last two YouGovs have found Johnson's lead diminishing, adding to the general – and largely unscientific – feeling that it's going to be very close and that Livingstone just might be gaining a little ground.

The get-Ken squad at the Evening Standard is, of course, still doing all it can to destroy the Labour man, with a series of decidedly far-fetched – not to say tedious - "exposes" recently. On the other hand, the unbiased scrutiny of the broadcast media has lately put Johnson under uncomfortable pressure. Amazingly, he still can't get his story straight about his "new Routemaster" policy as Jeremy Paxman, Andrew Neil and Tim Donovan (from 30 minutes in) have all revealed. This is a pity because somewhere amid the muddle there remains the grain of a good idea. There will be more studio debate on ITV tonight at 10.35. It was recorded yesterday: quite a rowdy affair, apparently.

There is, though, one other thing on which most insiders and experts appear agreed. It is that turnout will be crucial to the result. The small print of several polls has suggested that those who say they'll vote for Johnson are more certain to do it than those who say they'll vote for Livingstone. This makes sense given that older voters tend to favour the Tory, and they are more likely to make it to a polling station on 1st May than younger voters, who mostly prefer the Labour man. No surprises, then, that the incumbent is making so much of his recent youth offer and his cultural manifesto. And he's nearly twenty years older than Boris too!

By Dave Hill

Read more from Dave over at the Guardian, and on his mayoral blog.