When the state first moved to buy the worn stovepipe hat more than a decade ago, one historian marveled that it was “so emblematic of Lincoln” that “people would go crazy for something like that.”

But years later, the authenticity of the beaver-fur top hat was called into question in a series of articles in the Chicago Sun-Times with experts questioning whether it could be proven that it ever belonged to Lincoln — and whether it was worth the purported $6.5 million paid for it.

Now the foundation that runs the Abraham Lincoln Presidential Library and Museum in Springfield may be forced to let the market decide, after announcing that the hat and other Lincoln artifacts could go on the auction block to pay off loan debt.

The Abraham Lincoln Presidential Library Foundation revealed this week that it owes $9.7 million on a 2007 loan it used to buy the Barry and Louise Taper Collection, which includes the stovepipe hat Lincoln purportedly wore, as well as the blood-stained gloves he wore the night he was assassinated.

The foundation paid $25 million and borrowed $23 million, paying off about $13 million of the loan through private fundraising. The note comes due in October 2019.

Though the unnamed lender “has been quite helpful, we now face significant uncertainty about whether the foundation’s lender will be willing and able to refinance the loan at affordable terms,” the foundation said in a statement.

“If the foundation is not able to secure commitments in the very near future to retire most — if not all — of the remaining $9.7 million debt, it will have no choice but to accelerate the possibility of selling these unique artifacts on the private market — which would likely remove them from public view forever.”

The state operates and funds the Lincoln Presidential Library and Museum where the artifacts are on display, but the foundation that supports it is not state-funded.

Foundation officials say they have been in talks with Gov. Bruce Rauner’s office since last year — including a meeting earlier this week— about securing money from the cash-strapped state, but officials say they have received “no financial commitments.”

Rauner spokeswoman Patty Schuh called the museum “a jewel for the state.”

“We are certainly working with the Abraham Lincoln Library Foundation as they work through their options. We are listening to them and we are listening to their business plan,” Schuh said.

Rene Brethorst, the foundation’s chief operating officer, said they are “working hard to avoid” sale of the Lincoln items.

The foundation says it will “continue its private fundraising efforts and be prepared to discuss a financial plan that would include some state funding.” They claim to have made “three prior attempts to secure appropriations from the Illinois Legislature to help pay down the debt.”

The Taper collection also includes and an 1824 book containing the first known example of Lincoln’s handwriting, unpublished letters from Mary Todd Lincoln and items from assassin John Wilkes Booth.

It’s not clear how much items in the collection could fetch at auction. The prized stovepipe beaver-fur hat was valued at $6.5 million in 2007, but its authenticity has been called into question in recent years.

The Chicago Sun-Times first raised questions about the hat’s background in 2012 because the museum’s explanation of where it came from conflicted substantially with an affidavit from more than half a century earlier describing its ownership trail.

Concerns about the artifact’s legitimacy became so heated in 2013 that members of the state historic panel that oversee the museum debated having the Illinois State Police’s forensic lab conduct DNA testing to determine if the hat actually ever belonged to the 16th president.

The museum curator argued against it, snapping “This is a dead issue. Dandruff, bone, hair, forget it. It’s not there.”

Museum and foundation officials have insisted Lincoln donned the hat, though they acknowledged to the Sun-Times in 2012 that they could not pin down how the hat ended up in the hands of a farmer in the 1850s, and passed through the generations until it wound up in the collection the foundation purchased in 2007.

“In a court of law, there are different levels of assurance,” said James Cornelius, curator of the museum’s Lincoln Collection. “The Scottish legal system has guilty, not guilty and not proven. We elected in this country not to take that third option, in which the presumption of guilt is kind of heavy. I guess, if you want to be pushy about the hat question, you’d have to judge it in the not-proven category of Scottish law because it cannot be proven or disproven.”