City Council Speaker Melissa Mark-Viverito raised eyebrows Thursday when she said she plans to support Mayor de Blasio “if” he decides to seek re-election next year.

And she didn’t rule out running if he doesn’t.

De Blasio has been running for re-election for months and several council members have endorsed his bid.

“I’ve said already that if the mayor decides to run again, that I would support him,” she said during a WNYC radio interview.

When asked if she’d consider running if de Blasio didn’t, she left the door open.

“All options are open — I will leave it at that,” said Mark-Viverito, who is term-limited and must vacate her council seat in 2018.

De Blasio is facing multiple fund-raising corruption probes. He insists he has followed the law.

When asked to clarify the remark later in the day, Mark-Viverito told The Post she didn’t know whether or not de Blasio had made his re-election intentions known yet.