Labour's lead over the Conservatives would be wiped out if Boris Johnson took over from David Cameron, a poll published on Wednesday revealed.
A survey of 1,871 people conducted by YouGov for The Sun showed the Tories are currently trailing Labour by 31% to 42%. If a general election were held today this would help Ed Miliband secure a sizeable overall majority of 92 seats.
But if the Tories staged a coup against the prime minister and installed Boris as leader the party would be neck-and-neck with Labour with 37% compared to Miliband's 38% of the vote, results showed.
Labour would still win an election based on those poll numbers, but its Commons majority would be slashed to just eight.
So impressive is Boris' poll lead over the other main party leaders that YouGov's Peter Kellner described it as if Mo Farah had "not just won the 10,000 metre race at the Olympic stadium, but lapped all his rivals on the way to the finishing line".
"Nationally, a Boris-led Tory party would win 1.5 million more votes than a Cameron-led Tory party. Instead of a Labour near-landslide, we’d have a cliff-hanger," he said.
A separate online poll conducted by Usurv found that if forced to choose between the two men, 68% of voters would chose Johnson to be prime minister, while 32% would prefer David Cameron.
Today's poll will only add to the speculation that Johnson intends to return to parliament either before or after the 2015 general election in order to challenge for the leadership of his party.
In recent weeks the mayor has stepped up his attacks on the prime minister over suggestions that the government intends to perform a U-turn on its opposition to a third runway at Heathrow.
And over the weekend he was forced to deny rumours that he was involved in a imminent plot to oust Cameron by standing in a by-election in South London.
It was reported that Tory MP Zac Goldsmith, who is strongly opposed to the expansion of Heathrow, offered to quit his Richmond seat to allow Johnson to stand in his place.
On Monday Johnson upstaged the prime minister when the two men spoke at the end of a rally to celebrate the success of the London Olympics.