The ride-booking app Uber is fighting New York’s city hall, which wants to keep in check a fleet of vehicles that already far outnumbers the Big Apple’s trademark yellow cabs.

Townhall in the largest US city could vote as early as next week to limit increases in what it calls new for-hire vehicles (FHV) pending a study on their impact on traffic, and in particular traffic jams.

The limitation could be severe: an increase of just one per cent per year for companies with more than 500 vehicles, and five percent with those with between 20 and 499 vehicles.

“What is good for Uber may not be good for New York City,” said Wiley Norvell, a spokesman for city hall.

He cites figures: more than 20,000 Uber vehicles now operate in New York, compared to 13,587 yellow taxis.

And 2,000 new permits for for-hire vehicles are granted every month, and the FHV fleet, of which Uber cars are just a part, has shot up 63 per cent in size since 2011.

To back up its argument against unleashing more Uber cars, city hall cites such issues as quality of life, public health and businesses’ ability to thrive.

It notes that average traffic speed in Manhattan has gone down nine per cent between 2010 and 2014, going from 9.3 miles (15 kilometers) per hour to 8.5 miles per hour.

City hall says the New York’s streets cannot necessarily handle a “tide of new vehicles.”

Months of talks with Uber have gone nowhere.

City hall blames what it calls an “ideological clash.”

David Plouffe, a former aide to President Barack Obama and now chief strategist for Uber, made a special trip to New York this week for meetings with city officials. Tensions got even worse.

In recent days, Uber has gone all out with TV ads and a campaign of emails and petitions accusing Democratic Mayor Bill de Blasio of “pushing the agenda of his big taxi donors.”

“I think it is less about traffic congestion than it is about political contributions,” Plouffe told reporters.

The price of a medallion – the city-issued license required to operate a yellow cab – has dropped 23 per cent since 2013, when it topped $1 million.

Uber’s ads feature drivers from minority ethnic heritages and say the mayor’s proposals will destroy more than 10,000 jobs.

The ads also depict families in Queens or the Bronx, boroughs where it is hard to find a taxi.

“Vital services for thousands of New Yorkers may vanish,” says one of the ads.