The Union for Reform Judaism urged President Barack Obama to use the word “genocide” in describing the murder of 1.5 million Armenians.

Rabbi Rick Jacobs, the union’s president, made the call in an open letter he sent to Obama on Thursday, ahead of the centennial anniversary of what is widely known as the Armenian Genocide.

“Failing to call the slaughter of over 1.5 mission Armenians in 1915 ‘genocide,’” Jacobs wrote, “diminishes the suffering of those who were annihilated.”

Despite Obama’s 2008 pledge to recognize the Armenian Genocide as such, the White House has refrained from using the term, with officials citing the need to refrain from damaging relations with Turkey.

In his statement Thursday evening, Obama suggested he personally favored the term, but stopped short of using it as an official description, although he hinted that might change.

“I have consistently stated my own view of what occurred in 1915, and my view has not changed,” he said. “A full, frank, and just acknowledgement of the facts is in all our interests.”

Calling the murders “the first mass atrocity of the 20th century,” Obama notably cited the findings of Raphael Lemkin, the Jewish lawyer who coined the term “genocide” and praised Pope Francis for his April 12 pronouncement, which also used the term “genocide.”

White House national security advier Susan Rice urged Turkish Foreign Minister Mevlut Cavusoglu “to take concrete steps to improve relations with Armenia and to facilitate an open and frank dialogue in Turkey about the atrocities of 1915,” the White House said in a statement.

On Wednesday, the White House announced in a statement that it would send a delegation to Armenia for official commemorations of the “the Events of 1915.”

Led by Jacob J. Lew, Secretary of the Department of Treasury, the delegation also includes Rep. Jackie Speier (D-Calif., who said in a statement: “I will call it a genocide everywhere I go.”

In his letter, Jacobs praised Obama for sending the delegation but added that the use of the term followed also from Obama’s pledge, made during Holocaust Remembrance Day last week, to “never forget. Never again.”

Mindful of its relationship with Turkey, Israeli officials have also refrained from calling the Armenian Genocide that. However, as its relations with Turkey deteriorated, the Knesset in 2013 commemorated the massacres and called them a genocide.

Then Knesset speaker Reuven Rivlin, who is now Israel’s president, also called it a genocide repeatedly. Israel also sent a delegation to the official commemorations in Yerevan but officials have not repeated the controversial term — possibly out of consideration for Azerbaijan, a strategic partner for Israel that also opposes the terminology, along with Turkey.