Updated July 19, 2021 at 7:26 PM ET

A political power struggle for control of Haiti's government appears to have come to an end. Claude Joseph, who had previously served as prime minister and seized political control after the shocking assassination of President Jovenel Moïse, will step down, the country's elections minister confirmed to NPR.

Officially taking office as prime minister will be Ariel Henry, a 71-year-old neurosurgeon and public official who was appointed by Moïse to the prime minister post two days before the assassination, but had not yet been formally sworn in.

"It was part of the plan and wishes of late President Jovenel Moise that Ariel Henry should lead a new coalition to be prime minister and form a new government," said Mathias Pierre, Haiti's Minister of Elections, who confirmed the news to NPR by phone.

Pierre said the transfer of power, which was first reported via an interview with Joseph published by The Washington Post, will take place in a public ceremony Tuesday.

In a brief address to the nation posted online Sunday night, Henry called for political unity and said he would soon announce a consensus government that will lead the country until elections can be held to select a new president.

"I have the honor to address you in my capacity as prime minister, to launch a solemn appeal for national unity, for the union of our forces and for the cooperation of all to stop this race towards the abyss, to climb the slope and to protect our country from the many dangers that threaten it," he said.

Henry applauded the Haitian people for maturity in the face of "what could be called a coup d'etat," calling the assassination "unspeakable," "odious and revolting." He wished a speedy recovery for Moïse's wife Martine, who survived the attack and returned to Haiti Sunday on a private jet. Her right arm was in a black cast and she was wearing a black dress and black bullet-proof vest.

"I assure you that all light will be shed and that the culprits and their sponsors will answer for their actions before the law," he said.

The power struggle between Henry and Joseph began immediately following the assassination on July 7, but it was Henry who eventually drew crucial international favor in the form of a statement of support over the weekend from the "Core Group," a collection of ambassadors to Haiti, including the U.S. diplomat, along with representatives from the United Nations and the Organization of American States.

That appeared to be a change of position for the U.S., which had previously recognized Joseph as the prime minister.

"We have been encouraging for several days now Haitian political actors to work together and find a political way forward," White House press secretary Jen Psaki said at a briefing Monday. "We have not received an official notification through our embassy, but we welcome reports that Haitian political actors are working together to determine a path forward."

Henry and Joseph had been meeting for several days to come to an agreement. La Nouvelliste, Haiti's largest daily newspaper, reports the formal announcement will be made on Tuesday, with Joseph returning to his former position as foreign minister.

Henry is a neurosurgeon, trained at universities in France and Boston. He served as head of neurosurgery at one of Haiti's top hospitals.

He also served in two previous Haitian presidential administrations with multiple roles in the Ministry of Public Health, and later as Minister of the Interior and Minister of Social Affairs and Labor.

Now, Henry will step into one of Haiti's top political offices as multiple crises beset the country.

Haiti has been rocked by political turmoil, both since the assassination and in the months before as Moïse turned increasingly autocratic, cancelling elections and ruling by decree. Haiti's legislature is almost entirely vacant due to the lack of elections. Just last month, the head of the country's highest court died of COVID-19, upending that institution as well.

A wave of gang violence has gripped Haiti's capital Port-au-Prince, displacing thousands from their homes and keeping health care workers, teachers and other public employees at home due to fear of violence or kidnapping.

Even now, as Henry's rival Joseph has agreed to step down, some lawmakers and members of Haiti's civil society said the agreement lacks legal legitimacy.

"I don't think he can fix the problems we have now," said Samuel Madistin, a criminal defense and human rights lawyer, who believes Henry's appointment was problematic even before the assassination because of Moïse's moves to consolidate political power.

"We need elections that can bring stability in Haiti," Madistin said, but he also expressed worry that a rushed election, held amid Haiti's current wave of crime and gang violence, isn't the way to bring about democracy.

Henry alluded to the challenges in his address Sunday, in which he called on Haitians to cooperate and unify to overcome them.

"As prime minister, I appeal to the altruism of Haitian patriots to come out of themselves and face together the dangers that threaten us all and endanger the very existence of the nation," he said.

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