Mayoral candidate Muriel E. Bowser said Tuesday that she would undo newly adopted plans to redraw the District’s school boundaries, distancing herself from the education policies of the city’s current mayor and the schools chancellor she has vowed to keep on if elected.

Bowser stridently criticized the boundary plan, saying the city’s move to alter school assignments for tens of thousands of District students simply was “not ready.” The plan, the first major overhaul of the city’s school boundaries in four decades, emerged from 10 months of discussion and debate in scores of public meetings and among a citizen advisory council convened by the office of Mayor Vincent C. Gray (D). Gray adopted the new boundaries last week, with the goal of implementing them at the start of the 2015-2016 school year.

“His plan serves to exacerbate educational inequality and does little to move school reform forward faster,” Bowser, the Democratic nominee for mayor, said in a statement Tuesday.

Bowser’s position threatens to derail a process that city officials hope will bring coherence to the city’s haphazard school assignment policies and encourage investment in neighborhood schools. Education officials said Tuesday that they would continue implementing the boundary changes, including plans to use the new maps when the city’s school lottery opens in December, before the next mayor takes office. It is unclear what ramifications the school system would face if a new mayor upends the process, a move that could leave many families in limbo.

Bowser said her push to restart the process sets her apart from her most outspoken opponent on education policy, council member David A. Catania (I-At Large), who is running for mayor as an independent.

Catania said in a statement Monday that he would delay implementation of the boundaries for at least one year. He said he did not support the current plan in part because it would move some students from higher-performing schools to lower-performing ones.

Gray’s “recommendations are silent as to how we intend to improve those lower-performing schools,” Catania said. “Asking parents and guardians to take this leap of faith without more is asking too much.”

Gray spokeswoman Doxie McCoy said criticism from Bowser and Catania would not change the mayor’s stance. In releasing his plan last week, Gray suggested he was doing the next mayor a favor by making a politically perilous decision about boundaries before leaving office.

“The mayor has said that if either council member has any substantive proposals to put forward, we’ll certainly look at them,” McCoy said. “We stand by the plan and we urge the candidates to do the same. After more than 40 years of kicking the can down the road, it is time for city leaders to lead.”

The timing and tone of Bowser’s announcement stood in stark contrast to comments from Schools Chancellor Kaya Henderson, who has vocally supported the boundary change process.

On Monday, the District’s first day of school, Henderson praised the boundary overhaul as a much-needed transformation of a “hodge podge system.”

“I’m quite excited about it,” she said.

Improving predictability in school feeder patterns will help the city plan how to invest resources so that students in different areas have more consistent programming, she said.

The District has to work to improve the quality of schools and school-assignment policies simultaneously, she said: “It’s not one or the other.”

Bowser suggested Tuesday that the boundary battle falls outside of Henderson’s purview.

“The system is our system; it belongs to the residents of the District of Columbia,” Bowser said in an interview. “If you go back to the beginning of this process, the chancellor of schools was not involved in this process. . . . I don’t anticipate that the chancellor of schools will be involved in the boundary process moving forward.”

Deputy Mayor for Education Abigail Smith, who oversaw the advisory committee that developed the plan, said Tuesday that the city is moving forward with implementing the plan regardless of the political fallout.

“Obviously we knew as of April 1 that we were going to have a new mayor in January,” Smith said. “But there’s a lot of good work that the government has continued to do and will continue to do. I don’t think anything has changed.”

By next week, school principals will be sending home copies of their school’s new attendance boundaries in children’s backpacks, along with descriptions of how they will be phased in, Smith said. New maps are being uploaded to the city’s Web site, and by the time the online school lottery opens in December, families will apply for schools based on the new boundaries, she said.

Because of grandfathering provisions, the number of families that will be affected immediately is relatively small. But parents applying for preschool for the first time, for example, will get an in-boundary preference based on the updated maps.

Smith said that a new mayor could undo or roll back any or all of this work.

“The question is how disruptive will that be,” she said. She also questioned “what message that would that send to a community that has engaged for a year” in shaping this plan.

Matthew Frumin, a member of the advisory committee, said he hopes the new mayor would not scratch all the work that has been done. “It’s a process that was characterized by an enormous amount of public input,” he said.

Independent candidate Carol Schwartz praised aspects of the proposal in a statement Friday, including provisions that aim to minimize the concentration of at-risk students. She also said she was certain a new mayor could “make some changes” to the plan.

Bowser’s opposition was not entirely unexpected. Speaking in May to Democrats in Ward 3, she said she opposed all of three earlier proposals Gray was considering, including one similar to the plan he adopted last week.

In May, that position was popular with Bowser’s upper Northwest audience, where Gray’s plan would shrink the attendance zones for Alice Deal Middle and Wilson High, two of the city’s most sought-after schools.

In an interview Monday, Bowser singled out one aspect of Gray’s plan in particular as “problematic,” opposing boundary changes that reinforce geographic divisions, such as cutting off parts of her own Ward 4, east of Rock Creek Park, from attending Deal and Wilson, to the west, and cutting other boundaries off at the Anacostia River.

In her statement on Tuesday, she went further, saying that Gray’s boundary revamp would exacerbate inequality and that it lacked “necessary budgetary and leadership commitments” to bring about fair school assignments.

The plan was devised by “an advisory committee that made a recommendation to the outgoing mayor,” Bowser said. “We’re going to take a look at those recommendations with a fresh set of eyes.”