India, July 1 -- US President Donald Trump has threatened to slash federal funds for New York City if favoured mayoral candidate Zohran Mamdani does not 'behave himself' when elected to power.

"Let's say this, if he does get in, I'm going to be president, and he's going to have to do the right thing," Trump told Fox News.

"They're not getting any money. He's got to do the right thing," he said.

The 33-year-old politician captured 43.5% of the first round unofficial primary results.

Cuomo bagged 36.4 percent.

"I think it's very bad for New York. I don't know that he's going to get in, it is inconceivable that he is," Trump told Fox News, targeting the young politician.

"It's shocking. I used to say we will never have a socialist in t...