Fears of political tumult grow in the wake of the assassination.

“We talked about security, elections and a political accord,” he said.

On Thursday, the top United Nations official in Haiti, Helen La Lime, told reporters that she considered Claude Joseph, the interim prime minister, the person in charge of the country. She spoke via teleconference from Port-au-Prince, the capital, after briefing the United Nations Security Council about the Haitian crisis in a private meeting.

Adding to the challenges for a government in crisis, Haiti, a parliamentary democracy, has no functioning Parliament. There are currently only 10 sitting senators out of 30; the terms of the other 20 have expired. The entire lower house is no longer sitting, because the representatives terms expired last year. Long-planned elections were scheduled for later this year, but it was unclear when or whether they would take place.

The president of what remains of the Haitian Senate, Joseph Lambert, put out a news release on Thursday morning, saying that the Senate “reassures Haitians and the international community that everything will be managed by the national institutions, political forces and civil society to guarantee the continuity of the state and the republican order.”

A Haitian political analyst, Monique Clesca, said that Mr. Moïse had avoided opportunities to hold national elections, and that when the terms of the country’s mayors expired in January, he had installed his own supporters in those positions.

“The objective was always to be the supreme ruler,” Ms. Clesca said. “Eventually to be able to control the whole political apparatus.”

Haiti has a long history of political instability. The country has been rocked by a series of coups in the 20th and 21st centuries, often backed by Western powers, and has been marked by frequent leadership crises that have driven Haitians into the streets in protest.

While the United States and other nations have long supplied Haiti with much-needed aid and financial assistance, including help in recovering from a devastating earthquake in 2010, Western powers have also exerted an overwhelming influence over the country’s political destiny. The United States occupied the country from 1915 to 1934.