The Chicago Park District on Sunday accused Friends of the Parks of issuing an “outrageous” list of demands that is “nothing short of extortion” and will likely be the “final nail in the coffin” of efforts to keep movie mogul George Lucas’ museum in Chicago.

In a memo to its board members last week, Friends of the Parks Executive Director Juanita Irizarry outlined a list of demands in exchange for the group’s support for Mayor Rahm Emanuel’s backup plan to build the $743 million Lucas Museum on the site of a demolished, above-ground portion of McCormick Place East.

The demands stunned City Hall for their audacity. The list was leaked to the press and has yet to be shared with either the Park District or Emanuel, who met privately with Irizarry, Board Chairman Lauren Moltz and key board members last month.

Under intense public pressure to drop its opposition, Friends of the Parks is demanding that 5 percent of all revenue from the Lucas Museum be funneled into a fund for neighborhood parks. The group wants an ironclad guarantee that there will be no development along the lakefront for the next 100 years.

Other demands include improvements to DuSable Park in Streeterville; an agreement that a “significant number of jobs” at the Lucas Museum be set aside for minorities and low-income residents; and that Soldier Field’s south parking lot, once earmarked for the Lucas Museum, be converted into green space.

Read more about the Lucas Museum battle

On Sunday, Park District Board President Jesse Ruiz accused Friends of the Parks of deliberately attempting to sabotage the coveted project.

First and foremost is the demand that Emanuel abandon the Soldier Field site and return to his costly and controversial plan to tear down McCormick Place East.

That plan is clearly going nowhere in Springfield because it relies on $1.2 billion in new borrowing and extending the life of five tourism taxes to replace the lost convention center space.

Gov. Bruce Rauner has expressed serious reservations about the McCormick Place site and the new round of borrowing at a time when the marathon state budget stalemate has triggered severe cuts in social services and left public schools across the state in jeopardy of not opening on time this fall.

“At this juncture, the site on the parking lot between Soldier Field and McCormick Place is the only viable location for the Museum,” Ruiz wrote in the letter, obtained by the Chicago Sun-Times.

“We discussed this with you after you publicly rejected our plan to build on the McCormick East site and now, the political window to achieve that goal is closed.”

Ruiz branded the demand for 5 percent of Lucas Museum revenue “completely outrageous and totally unrelated” to the “stated opposition” that prompted Friends of the Parks to file a federal lawsuit challenging the mayor’s original site on Soldier Field’s south parking lot.

The park board president noted that “every other museum on the campus” receives a taxpayer subsidy and that the Lucas Museum would be the only institution that does not.

“You know from our many conversations that we are willing to discuss commitments from the Park District and City, but your attempts to demand money from the Museum are nothing short of extortion,” Ruiz wrote.

“Your new desire to add a new tax on museum visitors as ransom for your support is completely at odds with your stated goals.”

With Los Angeles and Lucas’ hometown of San Francisco breathing down Chicago’s neck, Ruiz all but threw in the towel on retaining a project that, he reiterated, would bring thousands of jobs and a cultural treasure to Chicago’s lakefront.

“Your uncoordinated effort and the leaked list of ill-informed demands unfortunately make clear that Friends of the Parks has no coordinated effort and no interest in actually resolving this issue,” Ruiz wrote.

“I’m afraid your list of demands — and the way in which your board leaked it to the press before we ever had a chance to discuss it — might be the final nail in the coffin,” Ruiz wrote. “Your legacy will have been to oppose the construction of the Barack Obama Presidential Center until community outrage drove you to retreat and now, to fight the Lucas Museum of Narrative Art, therefore denying the city, especially its children and residents who most need it, of untold opportunities that this museum would bring.”

Irizarry and Moltz could not be reached for comment. They were accused of being “sixteen months out of date” with a commitment already made to set aside museum jobs for minorities and low-income residents.

The demand for green space on the Soldier Field site was also after-the-fact and already part of the plan, the letter states.

Last month, Emanuel asked the federal appeals court to essentially order U.S. District Judge John Darrah to dismiss a Friends of the Parks lawsuit challenging the mayor’s original plan to give Lucas 17 acres of lakefront land near Soldier Field.

Darrah has already rejected the city’s motion to dismiss and sympathized with Friends of the Park’s central argument that a 99-year lease “effectively surrenders control” of prime lakefront property to a museum that is “not for the benefit of the public” but would “promote private and/or commercial interests.”

Friends of the Parks responded with a vow to carry on the fight in state court if the federal appeals court rules in Emanuel’s favor.

Before that legal maneuver, Emanuel offered to demolish McCormick Place East to make way for the Lucas Museum, only to have Friends of the Parks declare its intention to challenge that site as well.

That prompted Lucas’ wife, Chicago businesswoman Mellody Hobson, to say that she and her husband were “now seriously pursuing locations outside of Chicago” after a two-year process that she claimed had been “co-opted and hijacked” from the outset by “a small special interest group.”

Now the Lucas Museum saga appears to be entering its final phase. The only question is whether the museum’s new home will be San Francisco, which dropped the ball the first time around, or Los Angeles, where the museum would most likely be built on the campus of the “Star Wars” creator’s alma mater: USC.

Chicago Park District Board President Jesse Ruiz’s Letter to Friends of the Park