The next front in a week of battles over charter school space will be a planned protest today by parents opposed to housing an Arabic-language school in their children’s building.

The fights have been intensifying this year as the city plans to open 20 new small schools and a record 18 charter schools, many of them in buildings they would have to share with public schools.

Some already existing small schools also are looking for space as they grow, including an Arabic-language school, Khalil Gibran International Academy, which is expanding and set to move to a Fort Greene school, P.S. 287, despite the protests of some of that school’s parents, who will rally today at the Tweed Courthouse.

A hearing in Harlem last night over the fate of a charter school founded by a former City Council member, Eva Moskowitz, was the latest front in the space wars.

The Department of Education has recommended placing one of three new charter schools Ms. Moskowitz, CEO of the Success Charter Network, is opening in P.S. 123, a Harlem elementary school that the department’s data show has a capacity of 1,041 but is projected to enroll 540 students next school year.

Ms. Moskowitz brought hundreds of parents to P.S. 123 last night to make the case that adding a new charter school there would improve public education by improving parents’ options. She said 3,500 students have already applied to the three schools she aims to open by September.

Charter schools are free public schools that operate outside traditional regulations and are not guaranteed public space.

P.S. 123 parents are opposing the education department’s recommendation, arguing that the charter school would be an unwelcome intrusion.

The PTA president at P.S. 123, Antoinette Hargrove, said a new school would prevent programs the existing school is building from expanding, such as prekindergarten and a desired gifted and talented program.

“Soon there won’t be any public schools; isn’t that what they’re saying? They’re all phasing out,” Ms. Hargrove said in an interview before the hearing. “For what? Why not just all come together, try to fix the problem in the public schools, put more resources?”

Ms. Hargrove said she is receiving support from parents around her district, as well as from the teachers union, the NAACP, and several Harlem elected officials, including Assemblyman Keith Wright, state Senator Bill Perkins, and City Council Member Inez Dickens.

Ms. Dickens sent a letter to Schools Chancellor Joel Klein last month saying she is “against the installation of another school” in P.S. 123. The message was copied to Messrs. Perkins and Wright, as well as to Rep. Charles Rangel. Ms. Dickens’s special assistant, Lynnette Velasco, said yesterday that all of those elected officials have “expressed concern” about the charter school.

Mr. Wright issued a long statement yesterday decrying Ms. Moskowitz’s effort to place her school in P.S. 123 as divisive and predicting it will fail. “The way to protect our children’s educational opportunity is not by piggybacking off of our already overburdened public school system, nor is it by waging war against the current students and families of P.S. 123, as Mrs. Moskowitz is attempting to do,” Mr. Wright said.

A group of Harlem parents associated with Ms. Moskowitz’s school quickly shot back with their own statement. “I find Keith Wright’s statements to be ignorant, offensive, and alienating towards the community he is supposed to be serving,” one parent, Kyesha Bennett, said. “I expect more.”