(NewsNation) — A statewide solution is needed for homelessness, author Michael Shellenberger, founder of Environmental Progress, said on a new episode of “The Chris Cuomo Project” released Tuesday.

“There’s no reason that a relatively small city of San Francisco, fewer than a million people, can handle all of the mentally ill and drug-addicted people that come to San Francisco homeless looking for help,” Shellenberger said. “They should be able to get help from across the rest of the state.”

Mayors are “crying out” for a solution, he said. One city Shellenberger pointed to as handling homelessness the same way he would is Boston.

“They’re basically moving people into either temporary shelter, into permanent supportive housing, which is the holy grail for most progressives, but (Boston Mayor Michelle Wu) has the support of the whole state,” Shellenberger said. “That’s another problem that doesn’t fit onto a left-right axis, which is that proposal that you need a statewide solution.”

Shellenberger, who wrote the book “San Fransicko: Why Progressives Ruin Cities,” said he has interviewed hundreds of people living on the street. On the podcast, he said he tries to humanize those who may be dealing with mental illness or drug addiction while facing homelessness, while also showing their reality.

“Addiction is a psychiatric disorder. It hijacks the brain,” Shellenberger said. “At the same time, do I think people have personal responsibility? Absolutely.”

Conservatives, liberals and others have criticized “San Fransicko,” and some of the assertions made in the book.

At the same time, Shellenberger said, people from both parties have also agreed with his views, particularly his proposal of universal psychiatric care delivered at the state level.

“Psychiatric care has been a rare area of bipartisan agreement for decades,” he said.