Nearly 35 years after the renowned architect Louis Kahn designed a memorial to President Franklin D. Roosevelt to cover the southernmost 2.8 acres of Roosevelt Island, it appears his languishing vision could be realized.

The Franklin and Eleanor Roosevelt Institute is launching a final fund-raising push with the aim of collecting $40 million by the end of the year to build the memorial, a dramatic turnaround after several false starts over the past few decades.

The institute has already collected more than $5.1 million in donations. The first donation, $2.5 million from an anonymous donor, came in shortly after Governor Spitzer wrote a letter on May 30 encouraging the institute to take advantage of the momentum generated by construction on an adjacent park on the island. Construction on the park is expected to begin next spring or summer. The Roosevelt Island Operating Corporation of the State of New York is urging the institute to finish its fund raising in the next six months, so both can be built around the same time.

Although the institute is nearly $35 million away from its target, the executive director of the Franklin D. Roosevelt Memorial Four Freedoms Park project, Gina Pollara, said she is confident the money will be raised in time. “It’s going to happen,” she said yesterday, after poring over digital renderings of the memorial in her office near Herald Square. “We’re kind of in a now or never situation.”

A devoted fan of Kahn, who died in 1974, Ms. Pollara lights up when she talks about the memorial, beaming as she holds a chunk of granite from the quarry that builders will use in construction. She said she envisions a landmark that will draw people from around the world and put Roosevelt Island “on the map.”

“It’s really time for this to take place,” she said. “It really is the crowning piece that will make this island really and truly Roosevelt Island.”

Formerly known as Welfare Island, the 2 mile-long strip of land off the eastern shore of Manhattan was renamed after Roosevelt in 1973, in anticipation of the memorial. Although a model of the memorial was unveiled at the island’s dedication, it was never built, as a result of the city’s fiscal crisis in the mid-1970s. The project has been stalled ever since.

Not everyone is pleased with the memorial’s resuscitation, most notably a number of residents who say they would prefer the tip of their island to be a natural park, not one covered in stone.

The president and CEO of the Roosevelt Island Residents Association, Matthew Katz, said he is concerned that the memorial will cut off views to the east and west. A survey of residents found that most want “the greenest thing possible” in that space, he said.

“The Roosevelts were gods in my house, growing up,” Mr. Katz said. “Whether this is the appropriate memorial is another question.”

The association’s secretary, Sherie Helstien, said that by resisting Kahn’s memorial design, residents are trying to “save the last big community park” in the city. “I think a lot of us are just hoping they don’t get the money,” she said. “We don’t want that thing here.”

Visitors to the finished memorial would be greeted by a grove of copper beech trees at the outset and then could walk along one of two shoreline promenades or climb a set of stairs to reach an elevated grass field flanked by littleleaf linden trees.

The lawn would slope downward and the promenades upward, with all three paths meeting near the tip of the island, facing a bust of Roosevelt. Just beyond would be the open-air “four freedoms room,” named after a speech the president delivered in 1941. The room would have only two walls.

Ms. Pollara, who was the co-curator of an exhibition on the Kahn memorial held at the Cooper Union’s architecture school in 2005, considers the plan a masterpiece.

“You can choose to have a moment of thoughtful repose from the city or you can stand at the tip of the island and see this incredible view,” she said. “The skyline, it just explodes.”