Buoyed by celebrity support and a personal fortune, the billionaire led his Democratic challenger by more than 30 percentage points yesterday, running on a record of improving school test scores, lower crime rates, improved race relations and a local government budget surplus.

“He really has been a genuinely successful mayor,” Steven Cohen, Professor of Public Administration at Columbia University, said. “He got better as a politician. I think he actually enjoys it now.”

A former Democrat who switched parties to seek election, Mr Bloomberg is the archetypal “Rino”, or “Republican in Name Only”. As a political novice he narrowly won office in 2001 by clinging to the coat-tails of Rudolph Giuliani, his predecessor, after the events of September 11, 2001.

His approval rating plummeted when he raised property taxes and banned smoking in bars and restaurants. Two years ago nearly 60 per cent of those polled said that they would not want to have Thanksgiving dinner with him, but Mr Bloomberg turned a $6 billion (£3.4 billion) city deficit into a surplus within a year.

He survived when his project to bring the 2012 Olympics to New York was defeated. The latest poll showed that if Mr Giuliani were to run against Mr Bloomberg now, the billionaire would trounce “America’s Mayor” by 20 per cent.

Fernando Ferrer, the Democratic challenger, has tried unsuccessfully to tie Mr Bloomberg to President Bush, in a city where registered Democrats outnumber Republicans by five to one. “I’m not going to ask you to vote for me because I’m a Democrat; I’m going to ask you to vote for me because you’re a Democrat,” Mr Ferrer told a rally in Harlem.

One Ferrer campaign advertisement showed Mr Bloomberg, cash in hand, sitting on a donkey beside a grinning President Bush, but the Mayor has kept his distance from the Bush Administration on issues such as abortion and gun control, while mollifying the party by making hefty campaign contributions and hosting last year’s Republican convention.

Mr Bloomberg is expected to spend as much as $85 million on his campaign, about eight times as much as his rival.

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