Two people familiar with the decision said the president was expected to make the declaration as part of an official statement on Remembrance Day, which falls on Saturday. Both said it was possible he would change his mind before then, and issue a statement merely recognizing the event without describing it as genocide.
U.S. officials have also sent signals to allies outside the administration who have been pushing for an official declaration that the president will recognize the genocide, a third person familiar with the matter said.
The government of Turkey often registers complaints when foreign governments describe the event, which began in 1915, using the word "genocide." They maintain that it was wartime and there were losses on both sides, and they put the number of dead Armenians at 300,000.
Presidents Barack Obama and Donald Trump both avoided using the word genocide to avoid angering Ankara.
But Biden has determined that relations with Turkey and its president, Recep Tayyip Erdogan -- which have deteriorated over the past several years anyway -- should not prevent the use of a term that would validate the plight of Armenians more than a century ago and signal a commitment to human rights today.
The White House declined to comment on the decision when asked Wednesday. Press secretary Jen Psaki said the administration would "have more to say about Remembrance Day on Saturday."
The United States and its presidents have consistently avoided using "genocide" to describe the atrocity. But as a candidate, Biden said that if he were elected, "I pledge to support a resolution recognizing the Armenian Genocide and will make universal human rights a top priority for my administration."
But similar pledges have gone unfulfilled before. When Obama was running for president, he declared in a lengthy statement that he shared "with Armenian Americans -- so many of whom are descended from genocide survivor -- a principled commitment to commemorating and ending genocide."
But like presidents before him, the realities of diplomacy intervened once he took office. In all eight years of his presidency, Obama avoided using "genocide" when commemorating the April event. With Turkey positioned as a key partner in the fight against ISIS terrorists, the issue appeared even less palatable.
In 2019, the Senate passed a resolution formally recognizing the mass killings of Armenians from 1915 to 1923 as genocide. Prior to its passage, the Trump administration had asked Republican senators to block the unanimous consent request several times on the grounds that it could undercut negotiations with Turkey.
Trump attempted to cultivate a friendship with Erdogan, even as relations between Washington and Ankara soured over Turkey's purchase of a Russian-made air defense system and alleged human rights abuses by Turkish-backed forces in Syria.
Biden has not spoken to Erdogan since taking office, though the Turkish leader is expected to participate in a climate summit of 40 world leaders that Biden is convening on Thursday and Friday.