The Labour mayor’s plans to set limits on the amounts landlords can charge have so far been blocked by ministers.
But Mr Khan said that victory in the 7 May mayoral poll would give him an “undeniable and irresistible” mandate for the introduction of rent controls, given the prime minister’s previous statements on respecting the democratic will of the people.
There are 2.4 million private renters in London spending an average of around 43 per cent of their income on rent. After a 27 per cent rise in rents in the capital between 2010 and 2020, the average private rent for a one-bedroom home in London is now more than the average for a three-bed home in every other region of England.
Meanwhile, the proportion of Londoners renting privately has risen from 11 per cent in 1990 to 26 per cent in 2018, as the cost of buying a home has become unaffordable for many.
YouGov polling conducted for the Greater London Assembly in 2018 suggested more than two-thirds of Londoners favour caps on the amount landlords can charge.
At the launch of his re-election campaign at a housing estate in Hackney on Tuesday, Mr Khan was expected to say: “The case for rent controls is now absolutely undeniable. But Tory ministers have blocked us from introducing our plans for rent controls in London - and have simply said no. They have refused to give us the powers we need to make rent controls happen.
“That’s why today, I am making the mayoral election on 7 May a referendum on rent controls – showing Londoners that I will stand up for renters.
“Because if Londoners re-elect me as their mayor on 7 May, I want no-one to have any doubt that it represents an undeniable and irresistible mandate for the introduction of rent controls in our city. The prime minister will have to give us the powers we need.
“If he refuses to do so, he will be denying the express democratic will of millions of Londoners who are crying out for rent controls. And as we have all heard Boris Johnson repeatedly say himself, the democratic will of the people must be respected and it is not for politicians to frustrate it.”
A report commissioned by the mayor last year set out how London could take on powers to bring rents down and create open-ended tenancies without undermining the rental market, in a similar way to cities around the world including Berlin and New York.
Details of his proposals have not yet been released, but it is understood the mayor would establish a new London Private Rent Commission, with renters on its board, to implement and enforce measures to control prices.
Dr Kristian Niemietz, head of political economy at the free-market thinktank the Institute of Economic Affairs, said: “Rent controls have never worked anywhere. They do not just fail to solve the problem they are intended to solve; they also create new ones of their own.
“If Sadiq Khan had any interest in solving London’s housing crisis, he would focus on the supply side. He could, for example, push for a review of Green Belt boundaries, and a relaxation of height and density restrictions.”
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