US special envoy for the Horn of Africa, David Satterfield, will step down from his role before summer, after less than six months on the job and at a time of persistent political turmoil in the region.
Payton Knopf, the deputy special envoy, will take over the post in an acting capacity, Reuters reported.
Mr Satterfield and Mr Knopf were set to arrive in Ethiopia on Wednesday, the State Department said, for meetings with Ethiopian government officials, representatives of humanitarian organisations, and diplomatic partners.
The State Department did not comment on Mr Satterfield's departure.
The news of Mr Satterfield's expected departure comes at a time of multiple crises in the region.
A more than year-long conflict in Ethiopia has sparked accusations of atrocities on both sides, while Sudan is in economic and political turmoil following an October regime change.
The frequent change of personnel also raises questions about the Biden administration's commitment to the region, particularly at a time when it is grappling with pressing foreign policy crises elsewhere, primarily the Russian invasion of Ukraine.
The region remains an "absolute priority" for the administration, a senior State Department official said.
Mr Satterfield, a long-time career diplomat with decades of experience, had replaced Jeffrey Feltman, another veteran US diplomat who had stepped down at the end of last year after about nine months in the job.
Mr Feltman continues to serve in an advisory capacity.
Two leading human rights groups last week accused armed forces from Ethiopia's Amhara region of waging a campaign of ethnic cleansing against ethnic Tigrayans during a war that has killed thousands of civilians and displaced more than a million.
Amnesty International and Human Rights Watch said in a joint report that abuses by Amhara officials and regional special forces and militias during fighting in western Tigray amounted to war crimes and crimes against humanity.
They also accused Ethiopia's military of complicity in those acts.
Ethiopia's government said it was committed to holding all those responsible for violations of human rights and humanitarian law accountable.
Amhara government spokesman Gizachew Muluneh told Reuters the allegations of abuses and ethnic cleansing in western Tigray were "lies" and "fabricated" news.
Last week, the US expressed concern about reports of ethnically motivated atrocities in Tigray and called for an end to unlawful detentions based on ethnicity.
In Sudan, the military takeover derailed a transition that had raised hopes of an end to decades of autocracy, civil conflict and economic isolation after former president Omar Al Bashir was overthrown in a 2019 uprising.