(AP) Haiti's first parliament in two years was formally installed Tuesday as President-elect Rene Preval prepared to take office and steer this impoverished nation toward stability.

Amid boisterous cheers from supporters, legislators in the Senate took the oath of office, following deputies in the lower house by a day.

Preval, who served as Haiti's president from 1996 to 2001, takes power Sunday in front of the parliament, which hasn't convened since former President Jean-Bertrand Aristide was ousted in a February 2004 uprising.

Stephen Benoit, a deputy from Preval's Lespwa party, said the body's biggest challenge will be finishing its four-year term _ something that's never occurred in Haiti's chaotic 202-year history.

"That's the first challenge, to last the four years without a coup d'etat, without the president saying you're not going to finish your term," Benoit said after deputies held their first legislative session. "The population is counting on us. We need to deliver and we need to deliver quickly."

But getting work done won't be easy.

Preval has had to reach out to rival parties for legislative support since Lespwa, which means "hope" in Creole, lacks a majority in parliament.

Preval told reporters Tuesday that he would work to form "cohesion" among Haiti's fractured society, including the former ruling Lavalas party of Aristide.

Rudy Heriveaux, a Lavalas senator, said the party was ready to work for "national reconciliation" but will call on Preval to release dozens of Aristide allies jailed without charge under the U.S.-backed interim government. Among those jailed is Aristide's former prime minister, Yvon Neptune, who is accused of orchestrating killings of political opponents but has yet to be tried.

He added that Lavalas would also seek Aristide's return from exile in South Africa.

Preval, a former Aristide ally, has said that Haitian law allows Aristide to return, but hasn't said if he would welcome back his one-time political mentor.