Just before Jane Castor retired as Tampa police chief last year, I asked her about what had to be the most ridiculous rumor going: Castor would one day run for mayor of the city where she was a cop for 31 years.

Crazy, right? What an unlikely next step, particularly for someone who seemed to keep herself decidedly out of the trip-wire politics of the town. Such vocational transitions have been known to occur — with success, even — but didn't this seem against the natural order of things, like dogs and cats, reporters and politicians, cops and elected officials?

And anyway, Tampa likes Democrats for mayor. Castor was a lifelong Republican.

She reacted to the question in her usual deadpan manner: The fact that a she's-running rumor existed, Castor said, "just makes me realize the drug problem in this city is much more dire than I anticipated."

Then, a more definitive no: "I'll leave that up to people who are politically astute."

Now, with Castor a year into retirement and busy with police chief consultant work in other cities, the talk persists. Actually, it's gotten louder. In a town abuzz with speculation on who's in the mix for mayor — even with Bob Buckhorn still in the chair for three more years — the Castor rumor lives, breathes, grows. So I ask her, expecting more is-this-town-on-crack, and instead, get this:

"I'm still exploring the possibility of that," says Castor, 56. "I know I've come a long way in the last year from 'the drug problem in the city's worse than I thought.' " Then, a caveat: "I know a lot of people will think 'exploring' is French for, 'I'm definitely running.' But I say what I mean — I haven't made any decisions."

So lets throw her name onto the speculative woodpile, which includes Tampa City Council members Harry Cohen, Yvonne Yolie Capin and Mike Suarez, Hillsborough Commissioners Ken Hagan and Sandy Murman, and probably a half-dozen others to come.

Oh, there were signs. A month after leaving office, Castor, a registered Republican since age 18, pivoted to Democrat. She said the switch was about her party drifting away from embracing diversity and treating everyone fairly.

"To see the changes in the Republican Party and to see some of the advances in the Democratic Party, I switched," says Castor, who has called herself a true moderate.

She also in recent years became a member of the exclusive Athena Society, made up of powerful Tampa women — lawyers, judges, doctors, CEOs, politicians. She's joined her first book club.

Castor wouldn't be the first female mayor, but would be the first openly gay one.

People who would like to see this happen point out that she's run a police department —why not a city? Castor would likely have to bone up on the more boring, nuts-and-bolts aspects, and she will get questions about a crime-fighting tactic during her tenure that meant eight of 10 bicyclists ticketed were black.

But mayoral contenders are very aware she remains a rock star, stopped to pose for selfies with strangers and a sought-after speaker.

"A very, very credible candidate," says former boss Buckhorn, "if she chose to do it."

Sue Carlton can be reached at carlton@tampabay.com.