Boris Johnson's lead over his opponent, Ken Livingstone, has narrowed to just two percentage points less than a month after his arch-rival was confirmed as Labour's mayoral candidate for the 2012 London election, according to a YouGov survey released today.

The polling, conducted during the week of the Conservative conference at the beginning of the month, bodes ill for Johnson ahead of the drastic coalition spending cuts to be announced on Wednesday.

Livingstone has made protecting Londoners from the cuts a key feature of his campaign, and has urged the capital's voters to "punish" Johnson for cuts imposed by his Tory ministerial colleagues.

A sample of 1,271 Londoners questioned during the week of the Tory conference, when Johnson held a re-election rally following his decision to stand again in 2012, showed 46% would vote for the incumbent, while 44% would vote for Livingstone.

Just 4% said they would vote for the Lib Dem candidate, who has yet to be selected, and a further 7% said they would vote for "some other" candidate.

Asked who they would vote for in a straight choice between Johnson and Livingstone, the mayor widened his lead slightly, with 46% saying they would vote for him, compared to 41% for his Labour rival.

The figures are in stark contrast to a ComRes poll conducted on behalf of London media organisations last month, just days before the announcement that Livingstone had beaten Oona King to become Labour candidate.

The September poll found 45% of Londoners favoured Johnson, compared to 27% for Livingstone, who held the mayoralty for eight years under he was ousted in 2008, and 9% for King.

Johnson has sought to distance himself from the coalition cuts in his regular Daily Telegraph column, by insisting that London's infrastructure projects should be protected in the spending review, as well as expressing doubts about one of the key arguments underpinning the government's economic strategy.

But amid reports that his public lobbying has paid off, with funding for London's Crossrail project now expected to be saved, Johnson appeared to rally behind the spending review today as he criticised those "droning on" about the cuts.

In today's Telegraph column he argued that the measures planned for the deficit reduction programme were not about shrinking the state, but about "growth, growth, growth".

He wrote: "For months now we as a nation have talked about cuts and nothing but cuts, with the morbid fascination of an Oprah Winfrey discussion of self-harm. We know we have to go through with the operation. But we don't know quite how extensive the slicing is going to be, and we have been kept so long in the waiting room while the surgeon counts his scalpels that the foreboding has been allowed to grow.

"That is why it is so vital – as soon as the comprehensive spending review is announced – that we stop droning on about cuts, and start talking about the reasons for these cuts. They are not about shrinking the state. They are about growth, growth, growth – creating the conditions for a sustained economic recovery, and an economic recovery is a function above all of confidence."

But his warm words came with a warning to leave London's rising house prices alone or risk worsening the housing crisis and losing the confidence of high earners in the capital.

The mayor warned the government that proposals to deliberately "flatten" the market could lead to a sharp spike in prices as the economy improved.

He warned that such move would be "risky" in the short term and predicted that asking the middle classes to "wean" themselves off house-price inflation was "unachievable" in the longer term.

"If you tell people it is government policy that their house should effectively fall in value, then you will punch that confidence in the solar plexus – and you will make them less likely to invest, to take on new ventures and new staff," Johnson wrote.

"If the housing market tanks, then the financial system tanks too. People will be unable to get the mortgages to buy new homes, and developers will be unable to get the finance to build them, and the problem of supply will get even worse."

Johnson urged ministers to focus their attention on building affordable homes – for rent as well as purchase – instead, to deal with the population growth over the next twenty years.