President Obama Broke Promise for Charity Donation, ISIS Hostage Family Says Parents of Kayla Mueller say president offered contribution but never delivered.

 -- President Obama will make a financial contribution to a memorial foundation for slain ISIS hostage Kayla Mueller, the White House said today, but a spokesperson couldn’t explain why he hasn’t donated in the 17 months since her parents say he made a heartfelt pledge to them.

Obama spokesperson Josh Earnest said the president “is aware” of the Kayla’s Hands foundation and added, “I would anticipate that they [the Obamas] would make a financial contribution to continue supporting it.”

But Earnest could not say whether the president had promised the Muellers that he would make a donation to the foundation, whose objective is to turn Kayla Mueller’s beliefs into action and “to further her humanitarian efforts both locally and internationally,” as its mission statement says.

“I wasn’t a part of the conversation. Obviously Mr. Mueller and the president were,” Earnest told reporters today.

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Carl Mueller told ABC News today that his family remains certain of what the president offered during the private meeting in Phoenix, Arizona, on March 13, 2015, which included Kayla’s mother Marsha and brother Eric.

“I think that’s a question the president himself has to answer, since Josh Earnest wasn’t there,” Mueller said.

As President Obama tried to console the parents of Kayla Mueller after she was killed in ISIS captivity last year, they say he offered to make a contribution to a foundation they had established in her name.

“I’m still waiting for that donation, Mr. President,” Carl Mueller said in an ABC News interview broadcast this morning on "Good Morning America," as part of an hour long investigation to be aired tonight on "20/20."

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“He asked what he could do for you,” recalled Marsha Mueller, Kayla’s mother, about a private meeting when the president traveled to Phoenix after their daughter’s death.

“He says, ‘You won’t know, it’ll be an anonymous donation but I will,’” recalled Kayla’s father.

The Muellers say no such anonymous donation has been received by the foundation, named Kayla’s Hands.

In a statement, a White House official said, “The president will continue to support the goals of the organization in different ways, including by making a donation, as pledged to the Mueller family.”

The president’s failure to, so far, live up to his word about the donation, the Muellers say, came after a series of missteps by the administration that they say failed their daughter.

“The president could have been a hero, but he chose not to,” said Carl Mueller.

Their then-24-year old daughter was kidnapped by ISIS in August 2013 in Syria, where she had accompanied a friend who had been hired to install communications equipment for a hospital run by Doctors Without Borders in Aleppo.

The Muellers say White House officials threatened them with criminal prosecution if they tried to pay the $6.2 million ransom ISIS had demanded for the release of their daughter.

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Over the July 4, 2014, weekend the president authorized a U.S. military raid by the elite special mission unit Delta Force to free the hostages. But the squadron of Special Forces operators discovered the hostages had been moved to another location just a few days earlier.

Later when several wealthy donors volunteered to contribute money for the ransom, the Muellers say a senior White House official refused their request for a letter that would guarantee the donors would not be prosecuted.

The White House declined to respond directly to the Muellers’ criticisms, but spokesperson Ned Price this week provided a statement to ABC News:

"The United States worked tirelessly to recover Kayla Mueller, as well as the other American hostages held by ISIL in Syria, using every tool at our disposal. In Kayla's case, these efforts included the personal involvement of senior Administration officials, including the Secretary of State, and extensive intelligence analysis that culminated in an attempted rescue operation by the U.S. Military," Price said.

"Despite our best efforts, we recognize these families were frustrated by and disappointed in the way their government supported them in their time of need. That is why President Obama ordered a comprehensive review of our hostage policy and the way we work with families. We relied on direct feedback, including from the Muellers, to inform the actions the President directed in June 2015 to create the Hostage Recovery Fusion Cell that brings under one roof law enforcement, intelligence, and military capabilities as well as the designation of a Special Presidential Envoy to coordinate diplomatic efforts. In addition, the Justice Department clarified its practices - stating publicly that it has never used the material support statute to prosecute a family for paying a ransom for the safe return of their loved one."

The president in June 2015 said it was “totally unacceptable” for his administration to threaten hostage families with prosecution. President Obama also said at the time that he told the Muellers and others “there have been times where our government, regardless of good intentions, has let them down.”

While reiterating the policy that the U.S. government will not pay ransom to terrorists, the president said, “Our government may assist these families and private efforts in their communications.”

The Justice Department, in its own public statement last year, said it had never prosecuted any “family or friends” for raising ransom money to send to terror groups.

The Muellers say President Obama twice refused to meet with them after their daughter was taken by ISIS and only agreed to see them after American hostages James Foley and Steven Sotloff had been brutally murdered by ISIS.

“He said, ‘I’m a father, I have two daughters. If that was my daughter being held, I‘d do everything I could to get her out. And I’m sure he would have. But we were told many, many times, ‘We’re doing everything we can, everything we can.’ And they weren’t,” Carl Mueller said in the ABC News interview.

ABC News' John Parkinson and Devin Dwyer contributed to this report.