NEW YORK >> For months, the clash has seemed inevitable: the professed disrupters of municipal transportation policy and the chief executive of the country’s largest city government, tussling over who should rule the roads of New York City.

In a few short years, the ride-hailing company Uber has swelled in influence by the day, placing thousands of new for-hire vehicles on the road.

And now, the administration of Mayor Bill de Blasio is moving to halt the runaway expansion, citing a classic urban scourge to make its case: The infusion of vehicles, the city says, appears to be clogging Manhattan traffic.

With a City Council vote expected as early as next week on a proposal that would place a cap on Uber’s growth, pending a study of traffic patterns, the sides have become entangled in a protracted struggle, on camera and off, over the future of mobility in the city.

City officials have defended the move as a sensible reaction to unprecedented upheaval in the taxi world, where the number of for-hire vehicles has grown by more than 60 percent since 2011. The yellow cab industry, which includes some of de Blasio’s most prolific campaign contributors, has pressured the administration to clamp down on Uber, a grave threat to owners amid the faltering values of the yellow-taxi medallion.

Uber has connected the dots unsubtly.

"I didn’t just fall off the turnip truck," a top operative, David Plouffe, said this week. "I think this is less about traffic congestion than it is about political contributions."

Uber’s leaders have said the maneuver would "break" them in the city, leading to unwieldy wait times as a growing pool of passengers seeks a near-stagnant supply of cars.

The company has aired television advertisements, starring Uber drivers, that portray de Blasio as an enemy to working residents, and flooded council districts with mailers denouncing members who support the cap.

Plouffe, former campaign manager for President Barack Obama, has been dispatched to New York City for a round of appearances and meetings, including an audience with the mayor himself at City Hall this week.

And Thursday, a "de Blasio" tab was added to the app in New York, allowing users to see projected wait times for cars if the legislation is allowed to go forward.

The administration has sought to frame Uber as the bully, not the bullied. It takes more than a bit of gumption, mayoral allies said, for a company valued at more than $40 billion to cast itself as the underdog taking on City Hall.

"Now we know where that ‘surge pricing’ goes," Wiley Norvell, a spokesman for the mayor, said after the television ads began, referring to the app feature that raises passenger rates in moments of high demand. He said the company’s "ugly and disingenuous tactics" would not dissuade the city from "looking out for the public’s interest."

The legislation would limit for-hire licenses based on company base size, allowing bases with more than 500 vehicles to grow by up to 1 percent during the study period, which is to end by September 2016. Uber, which operates seven of the 10 such bases in the city, said it was currently experiencing vehicle growth of roughly 3 percent per month. Smaller bases would be subject to higher caps.

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