Boris Johnson received an undesired endorsement from embattled prime minister David Cameron today, as Labour tried to paint the pair as "two Tory peas in a pod".
An interview for today's Evening Standard saw Mr Cameron encourage other cities to vote for elected mayors so the country could have "many more Borises".
He went on to describe the mayor as "big hearted" and "his own man".
The comments played directly into the hands of Labour, which has been trying to link Boris with the Tories in Downing Street, who poll far below his level on popularity.
The storm over Jeremy Hunt and the double-dip recession resulted in a rare upswing in Ken's poll performance earlier this week.
"Boris Johnson is running a strategy to pretend he's not a Tory – that's why he never appears with David Cameron, that's why David Cameron's never on the stump with him," Labour leader Ed Miliband told BBC Radio 4.
"He is a Conservative, he acts like a Conservative, he wants Conservative policies."
Ken Livingstone added: "The David Cameron-Boris Johnson love-in on the eve of the election clarifies the very serious stakes for Londoners. It is two Tory peas in a pod.
"The Tory PM wants you to vote for the Tory mayor so that they can keep going with Tory policies that mean recession, fare rises and police cuts."
The Boris camp was also hit by twin rows on phone-hacking and tax avoidance.
Evidence published by the Leveson inquiry showed Boris' City Hall team were negotiating a sponsorship deal with News International when the mayor branded the phone-hacking scandal "a load of codswallop cooked up by the Labour party".
The firm offered £2 million for an academy school and further millions for a cable car across the Thames, which would have carried News International branding. The talks took place as it was engaged in a cover up of phone-hacking at News of the World.
When Boris was questioned about his links with News International earlier this week he branded the allegations "f**king bollocks".
Meanwhile, a Guardian report found a company linked to the Boris campaign had not paid tax in the UK for three years.
Canary Wharf-based international mobile phone company Lycamobile, which was used to canvass voters, is alleged to have failed to pay corporate tax in Britain.
The revelation is particularly embarrassing given the focus put on Ken's tax affairs over the course of the campaign.
Despite the problems facing the Boris campaign, most analysts, bookmakers and polls are still pointing to a Boris victory when London goes to the polls tomorrow.
Bookies Paddy Power started paying out on Boris after a flood of bets made the Tory an almost unbackable 1/12 winner.
In the final 24 hours before the payout, 94% of money taken by the firm was for Boris.
William Hill even went so far as to make Boris 2/1 favourite to win the 2016 mayoral election.
As Ken fought to wipe out Boris' lead – which some polls put in double figures – he was also engaged in an offensive to secure Liberal Democrat votes, with an email to thousands of Lib Dem voters asking them to give him their second preference.
In 2008, Ken secured 237,000 of his 303,000 second preference votes from Brian Paddick supporters, despite the candidate refusing to tell his supports to lend the Labour candidate their support.
Mr Paddick instead spent his time appealing to left-wing voters to desert Ken and offer him their first preference votes.
"Inequality has been a way of life for too long in London," the Lib Dem candidate said.
"Some of the most deprived places in the United Kingdom are just a stone's throw from the biggest financial centre in Europe.
"I don't believe in placing a limit on people's ambitions but I do believe in a floor beneath which people cannot be allowed to drop."