The State Ports Authority says it needs more time to sell a large piece of property it once planned to develop into a massive cargo terminal on Daniel Island.

The S.C. House of Representatives recently approved a one-year extension for the maritime agency to sell a nearly 500-acre tract on the Cooper River side of the island.

It marks the latest change to a 2009 state mandate that the property be under contract by the end of 2012 and a sale finalized by the end of 2013. The one-year extension was passed last year.

The latest request for more time to sell the site is part of the state's new fiscal year budget. That will need final approval from the Senate and the governor.

State Rep. Jim Merrill, R-Daniel Island, drafted the new extension, which would give the SPA until June 30, 2015, to sell. Merrill said the SPA needs more time to work with other groups involved in the sale.

"They need to line up all those entities involved to get this moved along," said Merrill, who is also a member of the Review and Oversight Commission on the Ports Authority.

He added: "There's a ton of things to be done, and we are working through it, and it's a long process."

The SPA wouldn't disclose how much it wants for the land.

Erin Pabst, a spokeswoman for the agency, said the property remains for sale, but it is not being actively marketed "as we work through issues" with the city of Charleston, the Daniel Island Co., residents and elected officials.

Pabst said the SPA has to resolve surveying to identify boundaries for dredge disposal, in addition to addressing issues like access to the property, zoning and plans for recreational space.

Matt Sloan, president of the Daniel Island Co., said he's open to continued talks with the SPA.

The firm, which is the island's main developer, owns access to the property the SPA wants to sell.

"The disposition of the SPA property is of significant interest for Daniel Island as well as the entire metro area," Sloan said in a statement. "We look forward to working with the SPA on creative solutions."

The SPA's request for more time comes as pressure mounts for the agency to sell its former marine terminal in Port Royal. The SPA said it's now in talks to sell the 369-acre former port near Beaufort to the town.

"The SPA is committed to selling both the Daniel Island and Port Royal properties in a manner that fulfills the board's fiduciary responsibility related to real estate sales as required by law," said Pabst, the spokeswoman. "A number of factors, including a difficult economy, have impacted the sale of the properties."

In terms of the Daniel Island site, it was part of 1,200 acres the SPA acquired in the early 1990s and planned to develop into a container terminal called Global Gateway. Opponents rallied lawmakers, who then pushed for the terminal to the former Navy base in North Charleston.

In 2006, the SPA put the land up for sale and received interest from 18 developers, but it took it off the market to re-evaluate its options. Part of the 1,200-acre site is used by the SPA for dredge disposal.

Elaine Worzala, director of the College of Charleston's Carter Real Estate Center, said selling such a large piece of land can be a drawn-out process that includes approvals, zoning and feasibility analysis.

She said holding the SPA to a deadline could remove leverage at the negotiating table.

"If you have a certain deadline for the transaction and the other party knows that, they will stretch it to the deadline," Worzala said. "They will wait until you're forced to sell and you'll take a lower price. That's basic negotiation."