Goldsmith will point to new analysis showing that not one of London's 16 Labour-led councils have delivered Khan's target of having 50 per cent of all new-build homes qualifying as affordable housing.
According to Goldsmith's campaign, the average Labour council delivered less than a third of their overall house building target as affordable homes.
The Goldsmith team pointed to Labour leader Jeremy Corbyn's own council, Islington, where the local authorities delivered 34 per cent affordable housing, against a 50 per cent target over three years.
"At a time when London’s population is set to hit 10m, we cannot afford a four year housing experiment that we know will fail," Goldsmith said. "Labour’s record on house building in communities across Greater London proves that a fantasy target chokes off new housing – the same will happen if Corbyn’s candidate Sadiq Khan is elected mayor."