(This February 14 story was corrected to change Aristide's former religious order to Salesian, instead of Jesuit in 14th paragraph)
By Joseph Guyler Delva
PORT-AU-PRINCE (Reuters) - A senator who served as interior minister under former president Jean-Bertrand Aristide was sworn in as Haiti's interim president on Sunday, a development met with elation by allies of the leftist leader who days ago were leading street protests.
Haiti cancelled a runoff presidential election in January amid often-violent protests over alleged fraud in the first round and after the opposition candidate boycotted the vote.
Former president Michel Martelly finished his term a week ago with no elected successor as a result. Instead, a deal was struck for the opposition-controlled parliament to choose a provisional president to oversee fresh elections quickly.
Factions of Aristide's Lavalas movement were heavily represented at the ceremony for President Jocelerme Privert, 63, at Haiti's national palace, which some had not visited since the ex-president was toppled 12 years ago.
"The last time I came to the palace was in 2003 when President Aristide was in power," said Ores Nixon, a street activist with a Lavalas splinter party who lives in the Bel Air slum in the capital, Port-Au-Prince.
"Now look at me, inside the national palace with a glass of champagne, celebrating the inauguration of our President Jocelerme Privert," he said.
By contrast, the ceremony and reception on the lawns of the building devastated in the 2010 earthquake were thinly attended by supporters of Martelly, or his party's candidate.
Aristide remained a potent symbol for the poor until the present crisis, but his influence was seen as fading as the movement he founded splintered into bickering factions and he largely vanished from public life.
As protests against Martelly and the elections gathered steam the factions reunited, however short-lived that may be.
Aristide's wife was at the ceremony in a rare political appearance, as was the current Lavalas presidential candidate.
"We have shown that we are able to overcome our differences and our infighting in the benefit of the general interest,” Privert said at the swearing-in.
Privert is a member of the Inite political party founded by ex-president Rene Preval, another estranged Aristide acolyte.
Privert vowed to engage all sectors in dialogue to complete the elections after an evaluation of the fraud allegations, and hand over to an elected president by May 14. Elections are set for April 24 under the deal struck last week.
After Aristide, a former Salesian priest, was forced from power by armed rebels in 2004, Privert was thrown into prison for two years on charges he organised a massacre of the president's opponents. The charges were later dropped.
One of the major challenges ahead will be to reach an agreement about who can participate in the election, with many parties rejecting the October results that led to a two-man race between opposition candidate Jude Celestin and ruling party favourite Jovenel Moise.
Activist Andre Fadot, who has led protests in favour of Celestin, was more cautious in his support of the interim government, warning at the palace on Sunday that free and fair elections should happen quickly.
It took two years to hold elections the last time there was an interim government in Haiti, after Aristide's ouster.
"Our presence here means Lavalas and Aristide are back in the palace. We are back in power and we won’t let it go," said Lavalas supporter Clausel Romey.
Reporting by Joseph Guyler Delva; Editing by Dominic Evans and Paul Tait