The New York City education department plans to close 14 low-performing schools at the end of the academic year, officials announced Monday, marking Mayor Bill de Blasio’s most aggressive effort to date to shutter struggling schools.

Nine of the proposed closures involve schools in the city’s “Renewal” program, which has marshalled millions of extra dollars and other support for troubled schools. Among the five other schools the city wants to close is the Urban Assembly School for Wildlife Conservation, the Bronx middle and high school where a student fatally stabbed a classmate in September and which students and parents have described as chaotic and plagued by unchecked bullying.

The closures will leave over 3,900 students searching for new schools to attend next fall, and more than 400 teachers seeking new jobs.

The city will also move to combine five Renewal schools that enroll very few students, and remove the middle-school grades from a school that currently serves grades 6 to 12. (Find the full list of proposed changes here.)

“The kids come first in any decision,” schools Chancellor Carmen Fariña said at a press conference, which the mayor did not attend. “All the decisions we made and we’re announcing today have that at the forefront.”

Unlike his predecessor in City Hall — who favored closing struggling schools and replacing them with new ones — Mayor de Blasio decided early in his first term to blanket low-performing schools with extra help, including teacher coaches, extended school days, health clinics, and funding to embed social-service providers in schools. The investments, de Blasio promised, would spur “fast and intense” improvements within three years.

The changes proposed Monday, which still must be approved by an oversight panel during its meeting in February, amount to an acknowledgement that it was not enough to turn around some of the city’s most struggling schools. De Blasio has said from the program’s unveiling that he would consider shuttering schools that failed to improve despite the help.

The closures and mergers would leave 46 schools in the turnaround program, which started with 94 schools in 2014 and now includes 78.

While the Renewal program was originally cast as an intensive three-year intervention, the remaining schools will be entering their fourth year in the program — and Fariña suggested it could extend for even longer.

“We’re not giving up on it at all,” she said.

But the city isn’t adding more schools to the program. While observers suspect the program’s huge price tag could be a factor, Fariña pointed to broader initiatives meant to infuse schools citywide with literacy coaches, Advanced Placement courses, and computer science.

“We expect that to make a big difference,” she said.

Evidence of the Renewal program’s success has been mixed. Schools have made only modest gains in test scores and graduation rates, researchers have found, while continuing to struggle with low enrollment and high turnover among principals and teachers.

Aaron Pallas, a professor at Teachers College who has followed Renewal closely, says that record raises an important question: What will the city do differently at the remaining schools?

“The schools that remain in Renewal are the ones I call the ‘hard cases’: These are schools that have not been making progress in the same ways others have,” he said.

Renewal officials and superintendents will soon ramp up their presence in the remaining schools, which will be expected to hit specific goals by next November, officials said.

While Monday’s announcement was de Blasio’s biggest school shake-up to date, the administration did close nine schools before the program reached the three-year mark this November. It also merged several other schools with ones that tended to be slightly higher performing. In the past, some school communities have mounted mostly unsuccessful campaigns to delay or stop the closure process, while others have been silent.

Families in the affected schools will receive letters about the proposals and personal phone calls Monday, officials said. The department’s enrollment office would work individually with the students to make sure they land in high-performing schools, they said — a difficult task once the traditional high school application deadlines have passed.

Officials said teachers would also receive help finding new placements. However, it’s likely that some will end up in the pool of teachers who lack permanent positions and act as roving substitutes — a costly group that the de Blasio administration has been trying to shrink.

In some cases, the education department is planning to open new schools in the place of the shuttered campuses, much like it did with J.H.S. 162 Lola Rodriguez de Tio in the Bronx, which closed in 2016 and saw I.S. 584 open in its place this fall.

The city’s teachers union, generally an ally of de Blasio, did not comment directly on the city’s plan to close schools — a policy it fought forcefully under former Mayor Michael Bloomberg. United Federation of Teachers head Michael Mulgrew blamed poor leadership, as evidenced by teacher turnover, for the schools’ potential demise in a statement.

“No matter how serious the challenges, if the leadership of a school is good, teachers will stay. If it isn’t, they leave,” Mulgrew said.

The United Federation of Teachers said half of the positions at new schools must be reserved for educators from the closed campuses. Fariña sounded a note of caution on Monday, noting that “nowhere near” that many teachers at I.S. 584 came from its predecessor, for example. (That could be due to teachers not applying to the new school or not having licenses that qualify them for the open positions, according to the union.)

Even as the city seeks to shutter schools in the $582 million Renewal program that have made insufficient progress since the program started, it is also creating a new pathway for improving schools to graduate out of the program. Twenty-one schools that have made academic and attendance gains will leave the Renewal program at the end of the academic year and become “Rise” schools, freeing them from intense oversight by the education department.

The nine Renewal schools the city plans to close are:

  • P.S. 50 Vito Marcantonio (District 4)
  • Coalition School for Social Change (District 4)
  • High School for Health Careers and Sciences (District 6)
  • New Explorers High School (District 7)
  • Urban Science Academy (District 9)
  • P.S. 92 Bronx School (District 12)
  • Brooklyn Collegiate: A College Board School (District 23)
  • P.S./M.S. 42 R. Vernam (District 27)
  • M.S. 53 Brian Piccolo (District 27)

The five other schools the city plans to close are:

  • KAPPA IV (District 5)
  • Academy for Social Action (District 5)
  • Felisa Rincon de Gautier Institute (District 8)
  • Urban Assembly School for Wildlife Conservation (District 12)
  • Eubie Blake School (District 16)

The schools the city plans to merge are:

  • Holcombe L. Rucker School of Community (District 8), becoming part of Longwood Preparatory Academy, another Renewal school
  • Entrada Academy (District 12) into Accion Academy
  • Middle School of Marketing and Legal Studies (District 18) into East Flatbush Community and Research School
  • Middle school grades of Gregory Jocko Jackson School (District 23) into Brownsville Collaborative Middle School

Alex Zimmerman contributed reporting.

Correction: An earlier version of this story cited an incorrect number of students — over 4,500 — who are affected by the closures. In fact, 3,950 students currently attend the 14 schools that the city has proposed closing. Just over 4,500 students attended the schools last academic year.