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The race to succeed Michael Bloomberg as mayor of New York is well under way. Awaiting the winner is an international profile and a budget of $70bn (£45bn). So how does the job compare with mayors of other big cities?

The new occupant of City Hall on Manhattan's Broadway will have more money to spend than a small country - and a population to match.

So perhaps it's no surprise that when the identity of New York's next mayor is revealed in November's election, it will make news around the world.

He or she will probably be the most powerful mayor on the planet, says Mitchell Moss, professor of urban policy and planning at New York University, because the job comes with unique executive powers - hiring and firing the people heading the city's key agencies like police and schools, while also setting the budget.

"The California governor doesn't even have that power. And the mayor controls the education of one million children. Education around the world is usually a national responsibility and not a city governor responsibility."

It's power that has come incrementally, ever since the British drove the Dutch out and gave the city control of its waterfront in the 17th Century. A recent addition came in 2002 when the vast schools system was reconfigured and made directly accountable to the mayor.

Contenders in New York Image copyright Getty Images Speaker of the New York City Council, Christine Quinn (above), leads polls

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is the leading Republican candidate Party primary elections are next month Interactive guide at New York Times

The person heading the largest city in the US has often enjoyed an international profile. Ed Koch - who ushered in the city's boom and put the near-bankruptcy of the 1970s behind it - was often photographed riding the subway or walking the streets.

And after 9/11, the no-nonsense figure of Rudy Giuliani came to represent the city and the country at its time of need.

But these days, it's a job that doesn't hog the international stage on its own. The ever-quotable London Mayor Boris Johnson appears on primetime US television, and his predecessor Ken Livingstone struck a controversial oil deal in Venezuela with Hugo Chavez.

The mayor of Paris, Bertrand Delanoe, drew praise for a free bike scheme which has been copied elsewhere. And the Olympic spotlight has now moved from Johnson to Rio's mayor, Eduardo Paes.

"Mayors without question are very much consistent with the spirit of the age - visible, figurehead urban leaders who are a much better fit in a world of 24-hour news and the need for celebrity visibility," says local government expert Tony Travers of the London School of Economics.

Bloomberg's forays into public health - the bans on smoking and trans-fats, and attempts to limit fizzy drink sizes - have inspired mayors the world over to intervene in health without fear of being accused of nannying, he says.

In the UK, cities like London, Bristol, Liverpool and Leicester have begun to adopt - with varying levels of public interest, admittedly - the American model of a directly elected mayor, and the same has happened in German and Italian cities. Dublin could be next.

But who is the most powerful? The New York mayor spends more money than London's, where much of the power is devolved to the 32 London boroughs (plus the City of London), including schools. But Bloomberg has little say over transport.