Oscar McKinney has seen seven mayors occupy City Hall since he started camping on San Francisco sidewalks more than three decades ago, and he’s got an opinion about every one. Those opinions were summed up in a derisive snort the other day as he lounged outside his tent on 13th Street near Van Ness Avenue.

“Not a single one of them ever had a good idea — except for Art Agnos when he started the winter shelters,” McKinney snapped. “Everything is too expensive. Nobody really cares about what happens to us out here. That goes for those clowns running for office right now.”

McKinney, 52, was swept away from his spot outside the Best Buy store on 13th — more commonly called Division Street — during the Super Bowl in 2016, along with hundreds of others in what had become the biggest homeless camp in the city’s history.

Division has stayed mostly clear since then — except for die-hards like McKinney, who has come back to Division like a homing pigeon since 1985, the last time he closed a door he truly called his own.

“Doesn’t matter to me what the next guy who gets elected mayor does. I’m an American, and I’ve got a right to be here,” he said. “If I could get a private landlord and rent of, say, $400, I might move inside. But until then? I don’t care who’s mayor.”

And that, in a nutshell, represents the Himalayan challenge facing the four major mayoral candidates on the June ballot as they try to outsell one another with their plans to clear the streets of tents and the penniless people on them.

How do you house people who are staunchly reluctant to move inside?

Unless they can come up with some way to put the more than 2,000 chronically homeless people like McKinney — longtime street people with a range of dysfunctions, from addiction to mental illness — under roofs they actually want over them, San Francisco’s crippling street problem will persist. And that doesn’t count the other 5,000-plus revolving door of homeless people found on the streets on any given night.

The four main candidates — Supervisors London Breed and Jane Kim, former state Sen. Mark Leno and ex-Supervisor Angela Alioto — all say they have a way to house those people. And quickly.

All of them roll out plans at campaign stops and on their websites, and the ideas boil down to two central, common goals: Clear tents off the streets, and create enough housing and health services to pull inside all of the chronic street dwellers, as well as much of the rest of the homeless population.

That’s pretty much what every mayor since Dianne Feinstein in the 1980s has wanted to do. Although several made progress — notably Gavin Newsom, with his Care Not Cash and Homeward Bound programs, and Ed Lee, who created the city’s first unified homelessness department — nothing has worked. The problem, much to the public’s dismay, appears to be worse than ever.

All the candidates say they wouldn’t exactly duplicate Mayor Mark Farrell’s late April order to clear the Mission District of tent camps in what amounted to a big, one-day push. They say some rules have to be in place, such as making sure sidewalks are passable and that people not be allowed to sprawl anywhere they want. But they prefer the practice of methodically clearing individual camps by getting their residents housing or services.

All but one of the candidates want to open more shelters. And they all have plans to quickly create more housing, both of the “affordable” variety — for low-income people struggling to stay inside or for homeless people who simply can’t afford typical rent — and of the “supportive” variety — for people who need social services as well.

Supportive housing is much more expensive — about $20,000 a year per resident in government-funded counseling and housing, versus up to $10,000 a year in mostly federal funding to merely help people with rent.

The political noise starts with the details.

London Breed comes right out and says she would clear the streets of tent camps in one year. She pledged to do this by attacking the problem from all angles — beefing up counseling outreach, building 5,000 new supportive, affordable and market-rate housing units a year, and opening more Navigation Centers, the specialized one-stop shelters that let people stay 24/7 and bring in pets, partners and belongings. She would also convert all of the city’s other shelters to round-the-clock operation so people don’t have to leave during the day.

She points to her success in 2014 in securing $2 million to rehabilitate vacant public housing units to house 179 homeless families as at least partial proof of her ability to succeed.

“I’m not messing around,” Breed said. “When I was acting mayor (between Mayor Ed Lee’s death in December and Farrell’s appointment by the Board of Supervisors in late January), I visited tent sites just about every day. I’m not trying to tear people apart in the camps, I’m trying to get them help for their needs and not leave them outside to die.”

Two of her main thrusts are advocating for state conservatorship legislation that would more easily allow courts to appoint guardians for chronically homeless people and opening safe injection centers where addicts can shoot up legally. These actions alone, she said, would reduce the spectacles of the mentally ill acting out in public and junkies fixing in the open.

“So much of homelessness is a public health issue in addition to being a public safety issue,” Breed said.

Breed also wants to push for the creation of modular housing, prefabricated units that can be stacked and built at nearly half the cost of conventional housing.

Mark Leno has the boldest claim of all. He says he can end street homelessness in the city by 2020.

Finding the money to do that, however, is complicated. He proposes crafting a regional homelessness and housing bond measure along the lines of the $1.6 billion bond passed in Los Angeles in 2016. He is also counting on $100 million authorized for the city under a 2004 voter-approved state tax measure for mental health initiatives, including housing that is currently tangled in a court fight.

Leno also promises to go through the city budget with a fine-tooth comb, starting out from scratch every year, evaluating every program for its worth — with one aim being to glean more cash for homeless aid.

“If we could squeeze just 3 percent greater efficiency out of our $5 billion general fund budget, that would get us $150 million more for homeless programs,” Leno said. “Everything is on the table.”

With the results of that and other funding, he said, he would quickly convert 1,500 vacant residential hotel units — some city officials estimate the number is actually closer to 800 — into supportive housing and expand the number of Navigation Centers. He’d also like to create 15,000 units of affordable, workforce and supportive housing units within three years.

“Right now we are just spinning our wheels and wasting a lot of limited public resources by not dealing with the problem, rather than the symptom,” Leno said. “How it is we haven’t expanded our shelter bed capacity? The immediate concern is to get people off the street.”

Jane Kim’s supervisorial District Six, which includes the Tenderloin and SoMa, contains fully 51 percent of the city’s homeless population. It has more open-air drug dealing and acting-out mental behavior than anywhere else. And Kim lives in the midst of it all — so she has an unusually intimate familiarity with the problem day by day.

Kim also spent a night at the second-biggest homeless shelter in 2012 and says she came away more determined than ever to tackle the needs of the street.

“Honestly, I didn’t know truly how badly off people were until I stayed in the shelter,” Kim said. “People are older and sicker than we realize, and shelters were built for people who are able-bodied, like me.”

Since then, she has successfully pushed for full-time nurses to be stationed at the city’s single-adult shelters and expansion of the city’s medical respite center, and advocated for new shelters all over town. In her determination to be mayor, she doubles down on those actions — proposing 1,500 new shelter beds; an expansion of the Behavioral Health Court, which directs addicts and mentally ill people to programs instead of jail; and expansion of hospital beds for acutely sick street people.

“I’ve never met a homeless person who didn’t really want services or housing,” Kim said. “We can do better.”

She pointed out that about half of the city’s $300 million or so annual spending on homelessness actually goes toward housing people. The rest is spent on outreach counseling, food programs, shelters and other services meant to move people inside or to make their lives more livable on the pavement.

“So we’re not spending nearly as much as people think we are,” she said. “We can do better, but we’re going to have to make a significant investment if we really want to make a difference.”

Of the four, Angela Alioto has the most experience grappling with homelessness. In 2004 she created, at Newsom’s behest, San Francisco’s 10-year plan to end chronic homelessness, which was then required of all communities to get maximum federal funding. And though its aim of housing every long-timer on the street by 2014 failed, that effort did pull 19,500 homeless people off the city’s streets — roughly equivalent to emptying the Noe Valley neighborhood of its residents.

Those chronically homeless people were shepherded inside by creating thousands of units of supportive housing, along with intensive street counseling to steer people toward services or bus tickets home to family and friends. Alioto wants to ramp up those same techniques. Her main disagreement with the other candidates is about shelters.

“I hate shelters. I would get rid of them,” she said. “We need to spend that money on housing, housing, housing — first. Period.”

The other candidates view the city’s 2,500 adult, youth and family shelter beds as necessary stepping-stones to housing. And though many homeless people don’t like the rules or sketchy people at a typical shelter, most will admit it’s safer than sleeping outside in the cold. They especially like Navigation Centers.

Alioto said that upward of 40 percent of the city’s approximately 2,000 to 3,000 chronically homeless people are so mentally ill or drug addicted that they should be put into psychiatric or rehabilitation facilities. The rest, she said, could be housed by quickly converting about eight empty buildings in the city into supportive housing, at about $3 million per building — translating to about $24 million to rehabilitate all the buildings, but then millions more annually to maintain them after that.

Last month, when Farrell’s operation scrubbed the Mission free of tents, McKinney’s little colony was among the first to be swept away. But the night before the cleaners came through, McKinney packed up to avoid the rush.

Where did he go? A few blocks away.

“They move me around, and I can understand that,” McKinney said. He winked. “But I always come back. And I don’t really care who’s mayor.”

Kevin Fagan is a San Francisco Chronicle staff writer. Email: kfagan@sfchronicle.com Twitter: @KevinChron