Mamdani, a 34-year-old democratic socialist, already faces intense scrutiny, even before taking office in one of the country’s most scrutinized political jobs. Republicans have cast him as a liberal boogeyman. Some of his fellow Democrats have deemed him too far left. Progressives are closely watching for any signs of him shifting toward the center.

On Jan. 1, he will assume control of America’s biggest city under that harsh spotlight, with the country watching to see if he can pull off the big promises that vaulted him to office and handle the everyday duties of the job. All while skeptics call out his every stumble.

For Mamdani, starting off strong is key, said George Arzt, a veteran Democratic political consultant in New York who worked for former Mayor Ed Koch.

“He’s got to use the first 100 days of the administration to show people he can govern,” he said. “You’ve got to set a mindset for people that’s like, ‘Hey, this guy’s serious.’”

That push should begin with Mamdani’s speech on the day of his inauguration, where Arzt said it will be important for the new mayor to establish a clear blueprint of his agenda and tell New Yorkers what he plans to do and how he plans to do it.