PMC Property Group is seeking a tenant for an office tower it wants to build on land beside its River Walk apartment complex, the latest in a spate of new commercial high-rise proposals for western Center City.

The proposed tower would rise on a narrow, roughly half-acre strip between John F. Kennedy Boulevard and SEPTA Regional Rail tracks, according to a brochure prepared by real estate firm Newmark Knight Frank, which is marketing the project.

NKF broker Craig Scheuerle said that the tower’s ultimate size will depend on leasing demand but that it is expected to fall between 200,000 and 500,000 square feet. PMC is prepared to break ground once it secures an anchor tenant willing to lease as little as 75,000 square feet, he said.

The project site at 2301 JFK is about a block north of where developer Parkway Corp. plans to begin work soon on a 19-story headquarters tower for law firm Morgan, Lewis & Bockius LLP, which would be Center City’s first new commercial office building not related to Comcast Corp. in more than 20 years.

Parkway has been working on another office building proposal on land it owns nearby at 20th and Arch Streets, while Brandywine Realty Trust recently disclosed plans for a 23-story commercial and residential tower on the 2100 block of Market Street.

PMC’s proposed development site is part of a seven-acre tract it bought along JFK between 20th Street and the Schuylkill in 2015. Its River Walk apartment complex, with about some 600 dwellings across two buildings, is under construction on a waterfront section of that tract.