Haitian Prime Minister Garry Conille abruptly resigned his post Friday, giving the country a new political crisis that is likely to distract the government and further delay efforts to rebuild from the devastating January 2010 earthquake.

The prime minister's resignation had been rumored for weeks, but it still sent shockwaves through a country accustomed to political turmoil. President Michel Martelly addressed the nation in a televised speech, thanking Conille for his service but giving no word on whether he had chosen a successor.

"Of course, I regret that the resignation occurs in a context in which the country is beginning to take off," said Martelly, whose first two picks for prime minister failed to win approval in parliament last year, largely paralyzing the government for the first five months of his term.

Conille's departure means Haiti will not have anyone to run the day-to-day operations of the government in the troubled country, a situation that will likely last at least for weeks before Martelly and the opposition-dominated Parliament can agree on a replacement.

It is a situation that observers fear will prompt international donors to withhold aid pledges and prevent action on the contracts necessary for reconstruction from a quake that left much of the capital in ruins.

"Haiti doesn't have any give, there's no cushion," said Mark Schneider, a senior vice president and Haiti expert with the nonprofit think tank International Crisis Group in Washington, D.C. "Anything that in another country is just a setback becomes a major setback because the challenges are so great."

The massive 2010 earthquake yielded an outpouring of sympathy and support that nearly matched the scale of the disaster's destruction. Donors pledged $4.5 billion in aid but only about half of that amount has been released and Haiti has hobbled from one crisis to the next, which has made rebuilding a piecemeal effort.

One of the donors, the World Bank-run Haiti Reconstruction Fund, has more than $100 million on hold pending the government's approval of projects to be carried out in a transparent and coordinated manner.

Josef Leitmann, administrator for the Haiti Reconstruction Fund, conceded that the "instability doesn't instill confidence" among donors but that the agency would "work with the government that's still in place _ that's the presidency and the parliament."

Others were more concerned. Senate president Simon Dieuseul Desras warned that the loss of the prime minister would create a political vacuum.

"This is not what the population was waiting for, that the Parliament and president's office are in conflict," Desras told The Associated Press at Parliament. "Today is a waste of time. We must start all over again and we don't know how long it will take to have another prime minister again."

At least two candidates were being considered as a replacement, including Foreign Affairs Minister Laurent Lamothe and Ann-Valerie Milfort, the interim head of the now-defunct Interim Haiti Recovery Commission, according to a government official who spoke on condition of anonymity because he was not authorized to release the information.

Conille, a physician who previously served as an aide to Bill Clinton in the former U.S. president's role as U.N. envoy to Haiti, was ratified by the opposition-dominated Parliament in October after Martelly's two previous picks for prime minister failed to win support from lawmakers, delaying the formation of a government by about five months.

Conille's resignation may have stemmed from disagreements with Martelly and his inner circle. It also may have been prompted by a dispute among government officials over whether any of them have dual nationality, which the nation's constitution prohibits for senior government officials. Many officials in Haiti and elsewhere in the Caribbean spend considerable time overseas.

A commission of lawmakers has been investigating allegations that Martelly administration officials may have citizenship in the U.S. or elsewhere. Conille and other officials have turned over their passports and other documents to the commission, but the findings of the investigation have not been announced.

Conille told The Associated Press after a news conference last week that he and Martelly were on good terms despite rumors to the contrary.

"I have a good working relationship with the president," he said, after announcing that he planned to audit millions of dollars in contracts awarded by his predecessor. "Haiti is a big country of rumors."

Opposition Sen. Kely Bastien said Friday he saw signs of division between Conille and his government last week when the number two official went before Parliament to answer lawmakers' questions about dual nationality but didn't show up with his entire Cabinet.

"Prime Minister Conille showed that he didn't have control over his government, and that's why he resigned," Bastien said.

Even though Conille said he was on good terms with Martelly and others, foreign diplomats raised concerns in recent days and weeks that he was at odds with other branches of government.

On Friday, Mariano Fernandez, the head of the United Nations peacekeeping mission in Haiti, issued a statement saying the rifts had taken over "conciliation" to the "detriment of the country."

Fernandez and the U.S. Embassy in Port-au-Prince stressed the need for Martelly and Parliament to work together to quickly name and approve a new prime minister so that Haiti can schedule legislative and local elections for this year. The terms of 10 senators, or one of third of the Upper Body, are slated to expire this year.

Martelly said in his public speech he had been in contact with Desras and the head of the lower Chamber of Deputies, and that his office and lawmakers are working to strengthen their relationship.

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Associated Press writers Evens Sanon in Port-au-Prince and Ben Fox in San Juan, Puerto Rico contributed to this report.