The Massachusetts Board of Elementary and Secondary Education voted Tuesday to expand the Alma Del Mar Charter School in New Bedford under a rare partnership between a public school district and a charter school.

The plan, which is pending city and state approval, would open a second K-8 campus in an empty public school building and serve as a neighborhood school, drawing students from the surrounding area rather than through a district-wide lottery.

The plan represents a departure from the normal order of charter school expansion. The new partnership's plan includes “an enrollment policy that is integrated with the district, permits the assignment of students to attend [Alma del Mar], and identifies a currently unoccupied facility that New Bedford will convey to [Alma del Mar] for use as a second campus,” according to a statement from the state board.

“You are saying to New Bedford: Hand over $7 million more in public school funds to Alma del Mar, and throw in a public building for free,” said Max Page, vice president of the Massachusetts Teachers Association, referring to state funds that would be diverted from the district to the school. “You have weaponized the charter expansion process, holding a gun to the head of the city, its students and its parents.”

Alma del Mar originally asked the board for nearly 1,200 seats, but was granted 450 new seats contingent upon its partnership with the New Bedford Public Schools.

If the partnership fails to materialize, the board would grant Alma del Mar an expansion of 594 additional seats.

The school will have to submit a draft enrollment policy to the board after negotiating with New Bedford Public Schools. The plan will also need city and state approval. The state legislature needs to approve a plan for enrollment by neighborhood and assignment rather than lottery.

Kristin Raffa, a New Bedford resident parent who attended Tuesday's meeting, has one child in a New Bedford public school and one at Alma del Mar. Raffa said she supports the expansion.

“The idea that a neighborhood with families could join us on this journey is inspiring to me,” she said. “I myself will do anything that I can to help the new school succeed.”

Alma del Mar opened in 2011 and had its charter renewed in 2016.

The school reports higher MCAS scores than both New Bedford and the state in English language arts and mathematics. Meanwhile, New Bedford is the fourth lowest-performing district in Massachusetts.

But critics of the expansion say Alma del Mar’s high performance comes at a cost— unusually high rates of suspensions for students, including those with special needs.

Alma del Mar has a nearly 17 percent out-of-school suspension rate for students with disabilities, compared with about an 8 percent rate for New Bedford Public Schools.

Alma del Mar’s in-school suspension rate for students with disabilities is 12.7 percent, significantly higher than the 1.1 percent rate for New Bedford schools.

“We believe that this high rate of suspension of students with disabilities indicates that these students likely are not receiving a free, appropriate public education,” said Jodi Guinn of South Coastal Counties Legal Services, echoing language found in federal law on special education.

Will Gardner, executive director of Alma del Mar, responded to criticisms about the school's disciplinary practices, saying leadership had hired an on-site, full-time social worker to address the higher rates of suspension.