New York Mayor Bill de Blasio on Monday called an order by Governor Andrew Cuomo to force homeless people indoors when temperatures drop below freezing a redundant mandate that the city already meets, the latest salvo in a feud between the two Democrats.

New York City's growing homeless population is the newest focus of the spat between Cuomo and de Blasio, who has publicly accused the governor of undermining his initiatives - ranging from control of city schools to crumbling public housing - for political gain.

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Cuomo signed an executive order on Sunday requiring officials throughout New York to force the homeless into shelters when the temperature is at or below 32 degrees Fahrenheit. The order goes into effect on Tuesday, when temperatures in the city were expected to drop to 18 degrees Fahrenheit on what weather forecasters said would be the coldest day so far this winter.

The mayor's administration first learned of the governor's order late Saturday night but did not obtain all the details until reading newspaper reports on Sunday, which made clear it referred to an existing state mental hygiene law, said the city's head of social services, Steven Banks.

At a news conference on Monday, de Blasio said the order "seems to simply reiterate what's already in the law and the power we already have to bring people in off the streets. And we use that power."

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The law applies only to homeless people who appear to be mentally ill, who would be taken off the frigid streets to a mental health facility for assessment by a medical professional. If the person is found to be incompetent and refuses to go to a shelter, he or she would be held at the mental health facility, not a shelter, Banks said.

He said the governor's order "does not mean that we have any authority to take off the streets anyone who is competent."

Banks spoke at a separate news conference about the mayor's latest effort to reduce homelessness. The city wants to end so-called "cluster" housing, which uses low-rent housing stock to shelter homeless families, and instead transform those families into renters of those units.

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Out of nearly 8.5 million people in New York, the largest city in the United States, about 58,000 homeless sleep in shelters on any given night. Nearly half of them are children. Between 3,000 to 4,000 people live on the streets, most of them single men who suffer from some form of mental illness, according to city data.

Seated on a Manhattan sidewalk and holding a cardboard sign describing himself as homeless, Chris Fitzgerald, 26, said he planned to sleep in a doorway as he has for the past three years and would not go to a shelter because he heard they were dirty and unsafe.

"Not fair," Fitzgerald said of the governor's mandate. "We should be able to decide what to do for ourselves."