St. Paul Public Schools Superintendent Valeria Silva confirmed Wednesday that her current contract will be her last — that she will be closing out a sometimes rocky tenure atop the state’s second-largest district in December 2018.

Her decision, she said, is about timing — she will be eligible for full-pension benefits then — as well as a recognition that after nine years as a superintendent, she will have completed “a long run, and it will be time for new leadership.”

She also is coming off a rough start to the 2015-16 school year, specifically an escalation in student violence that included brawls characterized by police as “riots” at two high schools and the choking into unconsciousness of a teacher at Central High. Silva said that the criticism that has come her way did not influence her decision to end her St. Paul career at what will be 33 years. But she acknowledged the toll that being a district leader can take.

“I work 14 hours a day. I work weekends. I am a public figure all the time,” she said. “It is a difficult and stressful job.”

Denise Rodriguez, president of the St. Paul Federation of Teachers, said that she had not been aware of Silva’s plans, and added flatly: “That really doesn’t change the work we’re doing right now with the district.”

She then shared the news with the union’s executive board members, one of whom, Stephanie Pignato, a teacher at Phalen Lake Hmong Studies Magnet School, said: “Our students remain our top concern and priority. We’ll work with whomever is in the superintendent’s position. Our students are here to stay.”

Efforts to reach Mayor Chris Coleman, who has championed Silva’s work on racial equity, and Jon Schumacher, the school board chairman who was one of four political newcomers elected last year on a wave of discontent over district leadership, were unsuccessful.

A month ago, the new board members surprised Silva at their first meeting with a list of proposed priorities for 2016 that would have required her to devise action plans on several key issues under aggressive timelines. The two sides have since adopted a more collegial stance on concerns they agree still have urgency. Again, Silva said that the combative start was not a signal to her that it was time to go.

In her view, she said, the election “is not punishment for me. It never has been. … That is what the community has a right to do.”

This year, Silva did not issue a State of the District address. But her presentation a year ago found her giving an impassioned defense to the changes that accompanied the Strong Schools, Strong Communities overhaul of the district. She also acknowledged the tensions that resulted from ambitious moves to shift more special-education students and English language learners into mainstream classrooms — moves that the teachers union said came without adequate staff support.

Middle schools saw a sharp rise in unruly behavior. But the situation has improved at two trouble spots, Ramsey and Murray middle schools, Silva said. She argued that people are more apt to criticize and to come to quick judgments about St. Paul schools without visiting the schools to see the progress that has been made.

A year ago, she flirted with a job possibility in Palm Beach County, Fla., and invited criticism again because she had just signed a three-year contract extension that would take effect in December. But she pulled out of the running, having decided, she said Wednesday, “it wasn’t the right time, and my heart was here.”

Now, with nearly three years left in her tenure, she does not see any downside in trying to get things done while at the same time being on the way out.

“The reality is it’s three years. It’s not like I have three months,” she said. “It’s three years, and we’re here for the kids.”

She has unfinished business to tend to, she said, and one item should resonate with critics: easing school-climate concerns.