Back in January, shortly after being named San Francisco’s interim mayor after the unexpected death of Mayor Ed Lee, Mark Farrell told The Chronicle’s editorial board his upcoming six months in office would be the end of his political career.

“This is it,” he said then. “Ask my wife.”

When I tweeted his comments, his wife, Liz Farrell, weighed in with a tweet of her own.

“This is a true statement,” she replied with a winking emoji.

But in an exclusive interview in the International Room at San Francisco’s City Hall last week, Farrell sounded more open to the idea of running for mayor in November 2019 or seeking a different political office down the road.

“I guess the answer is never say never, but it’s simply not part of my plans right now,” Farrell said.

I asked him what his wife thought of a 17-month break before seeking to reclaim the office.

“We haven’t really talked about it,” he said.

Uh-huh.

The Board of Supervisors named Farrell mayor on Jan. 23, and he talks adoringly of the job, calling it “an incredible honor.” He said the biggest surprise has been seeing how much change he’s been able to make in such a short time, especially compared with being one of 11 supervisors.

(To be fair, it would be hard to get less done than this current crop of supervisors, but I digress.)

“Until you sit in the mayor’s seat, it’s hard to conceptualize how much of an impact you really can have and, obviously, in a positive way,” Farrell said. “It’s been an incredible experience. ... We’re going to have a lasting impact on the city for years to come.”

Doesn’t exactly sound like a caretaker mayor biding his time until he can return to his job at his venture capital firm for good.

The scuttlebutt at City Hall is that Farrell will wait to see who wins in June — he declined to say whom he’s voting for — and how that person fares in the first few months on the job. The thinking is that if the new mayor is Supervisor Jane Kim, whose politics are far to the left of Farrell’s, he might challenge her next year.

“He really loves the job,” said Nathan Ballard, a Democratic strategist who has worked as an adviser to Farrell. “For the first time, his constituents are seeing his executive ability, not just his abilities as a legislator. When you’re mayor, you can act decisively and enact policy in a heartbeat.”

Farrell has acted decisively on many quality-of-life issues since taking office, sometimes irking the city’s famously liberal residents in the process.

He directed the clearing of homeless tent camps in the Mission last month and admitted in our interview that his team hasn’t tracked what happened to those people who declined to accept shelter beds.

Well, shelter mats.

A guarantee of seven nights on a mat on the floor of Next Door Shelter in the Tenderloin was the not-so-tempting carrot intended to lure longtime campers inside. Perhaps not surprisingly, just six people accepted the mats while scores more went on their way. To where? Farrell doesn’t know.

I asked whether success means knowing what happened to those who declined shelter beds or ensuring that sidewalks in the Mission are kept clear.

Farrell answered, “To your question, we’re doing less tracking of where they are. The main point is the sidewalks.”

Making our sidewalks passable and pleasant is essential, but if there’s no knowledge of where these folks are going, how will the city prevent new encampments from popping up a few blocks over?

Jeff Kositsky, director of the city’s Department of Homelessness and Supportive Housing, explained that the tent clearing was the culmination of a yearlong effort in the Mission.

Homeless outreach teams and other city officials repeatedly contacted 900 people living on the streets in the neighborhood. About two-thirds of them accepted beds in shelters or Navigation Centers, but the population began ticking up again this year, and those who remained on the streets were sometimes violent or causing neighbors anxiety.

Kositsky said one homeless person walked into the Sports Basement store on Bryant Street and punched a clerk in the face. Volunteers with the SPCA and Animal Care and Control, which is located in the neighborhood, were frequently harassed as they tried to walk dogs, he added.

“We said, ‘OK, we really need to resolve this,’” Kositsky said. “We’ve tried really hard.”

Farrell said those people who continually refuse services and wreak havoc on the streets simply can’t be allowed to remain living in tents on public sidewalks.

“We have gone from a point of compassion to enabling street behavior, and I do not believe in that,” Farrell said. “Just because someone desires to sleep in a tent forever on our streets does not mean the city should allow that.”

Farrell said he is considering ordering more tent clearings before his time in Room 200 is up, and that camps near Market and Castro streets could be next on the list.

“Absolutely, the intent is to do as many as we can,” he said. “The next mayor can continue it or discontinue it — that’s their prerogative.”

For a short-time placeholder, Farrell seems very focused on burnishing his legacy. He talked about how several initiatives — such as the new dirty needles cleanup team, an additional $12.8 million for street cleaning and new Bigbelly trash cans in the Castro — will help spruce up San Francisco’s notoriously filthy streets.

“I am actually very confident in a lot of the measures that I’ve put in place as mayor are going to have a lasting impact in cleaning up our streets,” he said.

(Side note: What is up with the city’s total lack of civic pride when it comes to littering? I saw a well-dressed man on a BART train the other day wait for the doors to open, place an aluminum can on the platform and retreat to his seat to keep riding. Even my little boys know better than that.)

I also asked Farrell about the burgeoning scandal at the Hunters Point Shipyard. Workers for Tetra Tech, the company hired to clear the site of nuclear residue and other toxic material, were found to have falsified soil samples.

Would Farrell support a family member or good friend purchasing a condo at the shipyard?

“No, not right now,” he said. “It’s awful.”

He has called for the retesting of the entire site, which seems like a no-brainer. Can you imagine the outcry if the same scandal happened in District Two — the Marina and Pacific Heights — which Farrell used to represent on the Board of Supervisors?

“I want to make sure the federal government acts quickly,” Farrell said. “Let’s just get results.”

Spoken like a man who knows his time in charge is quickly running out.

San Francisco Chronicle columnist Heather Knight appears Sundays and Tuesdays. Email: hknight@sfchronicle.com Twitter: @hknightsf