The White House says President Barack Obama plans to donate to the foundation honoring Kayla Mueller, shortly after her parents said the president 'had broken his promise'.

Kayla's Hands, a foundation in Mueller's name, seeks to honor her commitment to humanitarianism and serving the needy.

But Mueller's parents, Carl and Marsha Mueller, told ABC News in an interview airing Friday that Obama promised during a private meeting to make a contribution, shortly after their daughter was killed while in ISIS captivity last year.

'I'm still waiting for that donation, Mr President,' Carl said in the interview.

White House spokesman Josh Earnest says he won't discuss private presidential conversations. But he says Obama intends to contribute to the foundation in the future.

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The White House says President Obama plans to donate to the Kayla's Hands foundation honoring Kayla Mueller, shortly after her parents, Carl and Marsha Mueller (pictured), said the president 'had broken his promise'

President Obama (pictured with Kayla's parents) made the promise to Mueller's parents, shortly after their daughter was killed while in ISIS captivity last year

Earnest says the organization is consistent with the types of charities the president and first lady Michelle Obama have donated to previously.

He added that the pain and grief Mueller's family is expressing is 'entirely understandable'.

Marsha recalled that the president asked 'what he could do for you' during a private meeting when he went to Phoenix, Arizona, after their daughter's death.

Her husband added that Obama said the donation would be 'anonymous' to the Kayla's Hands foundation and assured them he would follow through.

Kayla's (pictured) parents said Obama said the donation would be 'anonymous' to the Kayla's Hands foundation and assured them he would follow through

The president has yet to make the contribution to the Mueller's foundation, but a White House official confirmed to ABC News that he still intends to do so.

In a statement to ABC, the 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 Muellers said several missteps by the Obama administration cost their daughter her life.

Carl told ABC that Obama could have been hailed a 'hero, but he chose not to'.

In the 20/20 interview, her mother Marsha also spoke of her heartbreak at seeing her then 24-year-old daughter as a helpless hostage.

‘I saw how thin she looked but I saw that her eyes were very clear and steady,’ she said. ‘It broke my heart but I also saw her strength.’

Mueller, of Prescott, Arizona, and her boyfriend, Omar Alkhani, were abducted by ISIS gunmen from a Doctors Without Borders vehicle near a hospital in Aleppo run by the humanitarian group on August 4, 2013.

At the time, ISIS were not as widely known as they are now and sent the clip of Mueller, one of their first Western hostages, in a bid to secure a millions of dollars in ransom.

Recently, an ISIS hostage video of Mueller was revealed – showing the murdered aid worker pleading for help from captivity.

Mueller, of Prescott, Arizona, and her boyfriend, Omar Alkhani (left), were abducted by ISIS gunmen from a Doctors Without Borders vehicle near a hospital in Aleppo run by the humanitarian group on August 4, 2013

Mueller is pictured with her family and pets as a youngster

The Muellers said several missteps by the Obama administration cost their daughter her life. The family also pinned their hopes on the non-governmental aid groups their daughter had worked for, including the Danish Refugee Council, Support to Life and the NGO Forum

The 22-megabyte video was sent to a friend of the aid worker, who passed it on to authorities, who then handed it over to her parents.

But although the video was received by the Muellers within weeks of their daughter’s capture, they didn’t begin negotiations for 10 months.

They pinned their hopes on the non-governmental aid groups their daughter had worked for, including the Danish Refugee Council, Support to Life and the NGO Forum.

KAYLA MUELLER REFUSED ESCAPE TO SAVE SEX SLAVES Daniel Rye Ottosen, a Danish freelance photographer, recalled how Mueller was paraded in front of the other prisoners as an example by ISIS butcher Jihadi John. Ottosen said the terrorist, who real name was Mohammed Emwazi, told the captives: 'She is much stronger than you guys. She's much smarter. She converted to Islam.' Interrupting her captors, Ottosen recalls Kayla saying: 'No I didn't.' That was in May 2014 while Mueller was being held in an oil refinery, one of the few times during her captivity that she had contact with other prisoners. For most of her ordeal, Mueller was kept in isolation, beaten, verbally abused, physically tortured or raped on an almost daily basis. Later that same year, after being transferred to oil and gas emir Abu Sayyaf's compound, a Yazidi sex slave who calls herself Julia, recalled how she concocted an escape plan and begged Mueller to come with her. The girl, who was just 13 at the time, said: 'I told Kayla, "We want to escape," and I asked her to come with us. 'She told me, "No, because I am American. If I escape with you, they will do everything to find us again." 'It is better for you to escape alone. I will stay here.' Advertisement

They said the groups told them the government has stepped in to help and would bring their daughter home safe.

Carl told ABC that his family trusted them all ‘like sheep’.

They didn’t start negotiating for their daughter’s freedom until May 23, 2014 – which is when they say Doctors Without Borders finally handed over an email address from Mueller’s kidnappers which they had got from one of their own workers who had been held hostage and freed.

Days later, they received an audio clip with Kayla’s voice telling them that she remains healthy along with the price of her freedom.

Recently, an ISIS hostage video (pictured) of Mueller was revealed – showing the murdered aid worker pleading for help from captivity

The video was received by the Muellers within weeks of their daughter’s capture, but authorities didn’t begin negotiations for 10 months

Mueller had been held in captivity for 18 months, and kept as a sex slave in a Syrian dungeon until she was killed in a Jordanian airstrike February last year. ISIS released images of this badly damaged building in which they claimed Mueller had been killed during the airstrike

In July of 2014, the president authorized a US military raid by the elite special mission unit Delta Force to free the hostages, according to ABC, but the squadron had discovered the hostages had already been moved.

The Muellers told ABC that several wealthy donors volunteered to contribute money for Kayla's ransom, but a senior White House official refused their request for a letter that would guarantee the donors would not be prosecuted.

In June 2015, Obama said 'totally unacceptable' for his administration to threaten hostage families with prosecution.

A spokesperson for the White House provided the network with a statement saying the US 'worked tirelessly to recover Kayla Mueller'.

'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,' the spokesperson said.