The Guardian understands that McLaren's original offer to the driver represented a little more than two thirds of his current deal, which is thought to be £15m a year. They have since come up with an incremental tweak, worth about an extra million. But that still leaves the Woking-based team well short of the £60m that Mercedes are prepared to offer him between 2013-15.
McLaren are worried by a financial climate that has substantially changed since Hamilton signed his current contract five years ago. They are also concerned that next year, for the first time, they will have to pay Mercedes for their engines – about £8m – and on top of that they are uncertain of the long-term plans of their main sponsors, Vodafone.
As far as Hamilton's agents, XIX Entertainment, are concerned, the decision is the driver's. But it is not a simple one. Hamilton, it seems, has not yet settled his mind one way or the other. When he does, it will not be based on money alone. He has to decide whether to stay with the team that has groomed him to stardom and the world title of 2008 or take a leap of faith and give himself the fresh challenge of joining the vast Mercedes operation, which is expected to be more competitive in 2014.
But if McLaren and Mercedes are really that far away from each other in money terms that is likely to tip Hamilton towards Mercedes, where he would also have greater commercial freedom to make deals away from the track.
Another complication for Hamilton is that McLaren, who have only won the drivers' championship once this century, appear to have the fastest car in the paddock. They have won the last three races, with Hamilton winning two of them, in Hungary and Monza last Sunday, to close on the championship leader Fernando Alonso. How would Hamilton feel if he walks away now, only to see team-mate Jenson Button win the title with McLaren next year?
McLaren badly want Hamilton to stay. However, the body language between the two sides has not been impressive lately, and after last weekend's Italian Grand Prix there were members of the team who, rightly or wrongly, felt that Hamilton had already decided to make a move.
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image: © McLaren