ST. LOUIS • City Alderman Lyda Krewson says she is ready to run for mayor.

Krewson formally announced her campaign Tuesday via an online video, adding a touch of clarity to a Democratic field that’s expected to expand following the surprise announcement that four-term Mayor Francis Slay won’t seek re-election in 2017.

“I think we need a mayor with integrity, intelligence, experience,” Krewson said during an interview Monday with the Post-Dispatch. “Somebody who will do the job with civility, determination, inclusion and fairness.”

Her video posted to YouTube included nearly those same words.

Krewson, the chief financial officer of PGAV Architects in downtown St. Louis, has served as the Ward 28 alderman for nearly two decades. The ward spans the city’s booming western central corridor neighborhoods, including the Central West End, DeBaliviere Place, Hi Pointe and Skinker DeBaliviere.

Krewson said her top priority, by far, will be public safety.

“I think we need to admit that we have a problem,” Krewson said. She said the city needs more police officers on the streets and in the neighborhoods.